Appellants are out-of-state students who were denied resident status for tuition purposes by Utah State University.1 After the University’s denial, appellants filed this suit. They challenge the constitutionality of the rules by which the University determines residency, and allege that the University’s decision was arbitrary and capricious. On cross motions for summary judgment, the trial court upheld both the rules and the University’s decision. We affirm.
The parties agree, as evidenced by their motions for summary judgment, “that there is no genuine issue as to any material fact.” Utah R.Civ.P. 56(c). Appellants George and Lori Frame met and were married in California in 1970 or 1971. At that time, George was temporarily stationed by the military in California, and Lori was a resident of California. Prior to being stationed in California, George had been a resident student in Alaska.
In the spring of 1971, the couple moved to Logan, Utah, and George Frame immediately enrolled at Utah State University. The Frames allege that during the next year they rented an apartment in Logan, opened an account with a local bank, registered to vote in Utah, and George obtained a Utah driver’s license. During that year appellants did not apply for resident status at the University.
In June, 1972, appellants moved to Tanzania, Africa, to do wildlife research for thesis and dissertation requirements at *1160Utah State. While in Tanzania appellants opened a bank account there, but stored some of their personal belongings in Utah and gave as their mailing address the Cooperative Wildlife Research Unit at Utah State.
In February, 1978, appellants returned to Logan. In March, 1978, both appellants registered at Utah State for classes beginning the following September. From March to September, 1978, appellants spent most of their time outside Utah visiting their families and traveling through several states to further their employment as lecturers, free lance writers, and photographers. During this time appellants continued to store some belongings in Utah; they listed the Wildlife Science Department as their mailing address; and George obtained a New Jersey driver’s license.
In September, 1978, appellants returned to Logan to recommence their schooling. They again rented local living quarters, opened a local bank account, registered to vote, and George obtained a Utah driver’s license and automobile registration.
Toward the end of that month appellants applied to Evan J. Sorenson, the Assistant Director of Admissions and Records, for Utah resident status so that they might pay the lower Utah resident tuition. Applying the State Board of Regents’ rules governing residency for tuition purposes, Sorenson ruled that appellants did not qualify for resident status because they had not lived continuously in Utah for one year prior to the quarter for which resident status was sought, and because they had come to Utah primarily to attend an institution of higher learning, and could not demonstrate by objective facts that Utah was their domicile. Appellants appealed that decision to the University’s Residency Appeals Committee, which affirmed Sorenson’s decision for essentially the same reasons.
In April, 1979, appellants again applied for resident status on the ground that over one year had elapsed since their March, 1978, registration at the University. Because appellants had been absent from the state for more than thirty days during the summer of 1978, Sorenson again denied their request on the ground that appellants had not resided continuously in the state for one year. On appeal, the Residency Appeals Committee affirmed.2
Having exhausted their administrative remedies, appellants filed suit in the district court in August, 1979, to compel the University to classify them as residents for tuition purposes. Appellants argue that it is a violation of due process and equal protection to deny resident status to them because they were absent for more than thirty days during the one-year period. Appellants also contend that the University’s reliance on their acceptance of out-of-state, “nontemporary” employment and their failure to purchase property in Utah as indicia of intent to establish permanent domicile in the state, violates the Equal Protection Clause. Finally, they contend that the Appeals Committee decision should be reversed because it was arbitrary and capricious.
I. REGENTS’ RULES
U.C.A., 1953, § 53-34-1 authorizes the Board of Regents to charge higher college tuition to nonresident students than to resident students. Section 53-34-2.2 defines “resident student” for tuition purposes:
(1) The meaning of the word “resident” for the purposes of this act shall be determined by reference to the general law on the subject of domicile, except that the following rules shall be observed:
(2) An adult who has come to Utah and established residency here for the purpose of attending an institution of higher education must maintain continuous Utah residency status for one full year prior to the beginning of the academic period for which registration as a resi*1161dent student is sought, and, in each case, must demonstrate by additional objective evidence the establishment of a domicile in Utah and that the student does not maintain a residence elsewhere.
Pursuant to subsection (7) of this section, the State Board of Regents has promulgated supplementary rules and regulations to assist institutions of higher education in classifying students as residents or nonresidents.3 Appellants challenge the constitutionality of these rules, which closely parallel the language of § 53-34-2.2. Rule I.A. sets forth the basic requirements for resident student status, including the statutory one-year residence requirement:
I. ADULTS — (Married students and single students 18 years and over)
A. In order to qualify as a resident student,
1. an adult must establish by objective evidence an intent to establish a permanent domicile in Utah; and
2. an adult student who has come to Utah for the primary purpose of attending an institution of higher education must reside in Utah for at least one continuous year prior to the beginning of the academic period for which registration as a resident student is sought.
Rule I.D. permits a thirty-day absence from the state without disqualifying a student from complying with the one-year residency requirement. That rule states:
D. Year’s Continuous Residency
A person who lives in the state for one year will not qualify as a resident unless the other requirements of paragraph A are satisfied. Short absences from the state, i.e., less than 30 days, will not break the running of the required one-year residence. Extended absences, i.e., longer than 30 days, especially if during such an absence the student works out of state or returns to the prior home of record for an extended duration, will break the running of the continuous year.
It is established law that a state may charge a higher tuition for nonresident students. E.g., Hasse v. Board of Regents, 363 F.Supp. 677 (D.Hawaii 1973); Clarke v. Redeker, 259 F.Supp. 117 (S.D. Iowa 1966). It is also established that a one-year period of residency may be imposed to qualify for resident tuition. Starns v. Malkerson, 326 F.Supp. 234 (D.Minn.1970), aff'd, 401 U.S. 985, 91 S.Ct. 1231, 28 L.Ed.2d 527 (1971); Sturgis v. Washington, 368 F.Supp. 38 (W.D.Wash. 1973), aff'd, 414 U.S. 1057, 94 S.Ct. 563, 38 L.Ed.2d 464 (1973).
Appellants do not attack any of the above propositions. Rather, they focus their challenge on the rule which precludes the establishment of residency if a student is absent from the state more than thirty days during the one year. They assert (1) that the thirty-day rule irrebuttably presumes, in violation of due process, that students who must travel outside the state for more than thirty days at a time are nonresidents; and (2) that the rule violates equal protection because there is no rational basis for distinguishing nonresident students who travel outside the state for more than thirty days from resident students.
II. DUE PROCESS
Rule I.A.1 requires that an adult seeking to qualify as a resident student “must establish by objective evidence an intent to establish a permanent domicile in Utah.” The evidence of permanent domicile may include evidence of any of the several factors listed in Rule I.E.,4 which *1162are typically utilized in determining domiciliary status. If, however, an adult comes to Utah primarily for the purpose of attending an institution of higher education, he is presumed to be a nonresident. As to such a person, Rule I.A.2 imposes the additional requirement that he establish one year’s continuous residency prior to the academic year for which he applies for residency status. Because of the difficulty in determining a student’s domiciliary intent when he applies for residency after coming to this state for the purpose of attending an institution of higher learning, the law establishes a rebuttable presumption that a person who enrolls in college “within a year after entering Utah from out of state” has entered the state primarily for academic reasons and therefore lacks domiciliary intent. Rule I.C.5 This presumption may be rebutted either through one continuous year of residence or by “[clearly demonstrating] that the move to Utah was not academically motivated.” Id. Rule I.D. provides that short absences from the state of not more than a total of thirty days do not disqualify one from meeting the one-year requirement.
Appellants contend that the thirty-day rule creates an irrebuttable presumption of nonresidence in violation of Vlandis v. Kline, 412 U.S. 441, 93 S.Ct. 2230, 37 L.Ed.2d 63 (1973). That case ruled that where a state is concerned with the factual question of residency, the state may not make the determination of the question turn on a permanent irrebuttable presumption. The Court held a Connecticut law unconstitutional which provided that (1) a student was presumed to be a nonresident for tuition purposes if his “legal address for any part of the one-year period immediately prior to his application for admission” to the state university system was outside the state, and (2) that a student’s status “as established at the time of his application for admission ... [was, as a matter of law, his] status for the entire period of his attendance at [school].” Id. at 442-43, 93 S.Ct. at 2231-32. In holding that the irre-buttable presumption violated due process, the Supreme Court stated:
In sum, since Connecticut purports to be concerned with residency in allocating the rates for tuition and fees in its university system, it is forbidden by the Due Process Clause to deny an individual the resident rates on the basis of a permanent and irrebuttable presumption of nonresidence, when that presumption is not necessarily or universally true in fact, and when the State has reasonable alternative means of making the crucial determination. Rather, standards of due process require that the State allow such an individual the opportunity to present *1163evidence showing that he is a bona fide resident entitled to the in-state rates. Since [the law] precluded the appellees from ever rebutting the presumption that they were nonresidents of Connecticut, that statute operated to deprive them of a significant amount of their money without due process of law.
Id. at 452, 93 S.Ct. at 2236.
Vlandis does not control the instant case. The law that Vlandis invalidated established an irrebuttable presumption of nonresidency that lasted the entire period that a student attended school.6 Under Utah law, by contrast, an out-of-state resident may, at any time after his arrival in the state, establish himself as a bona fide resident or domiciliary of the state by overcoming the rebuttable presumption of non-residency. In this case, appellants could, by living continuously in the state for one year and by meeting the other tests for determining domicile, establish themselves as residents.
The requirement that the one year may not be interrupted by more than thirty days of absence is not prohibited by Vlan-dis. Since a flat one-year presumption of nonresidency is valid, Starns v. Malkerson, 326 F.Supp. 234 (D.Minn.1970), aff'd, 401 U.S. 985, 91 S.Ct. 1231, 28 L.Ed.2d 527 (1971); Sturgis v. Washington, 368 F.Supp. 38 (W.D.Wash.1973), aff'd, 414 U.S. 1057, 94 S.Ct. 563, 38 L.Ed.2d 464 (1973), it follows that the thirty-day grace period must necessarily be valid.
III. EQUAL PROTECTION
A.
Both appellants and the University agree that the thirty-day rule neither jeopardizes a fundamental right nor creates a suspect classification. Therefore, equal protection of the laws requires only that the classification created by the rule bear a rational relationship to a legitimate state purpose. E.g., San Antonio Independent School District v. Rodriguez, 411 U.S. 1, 93 S.Ct. 1278, 36 L.Ed.2d 16 (1973); Dandridge v. Williams, 397 U.S. 471, 90 S.Ct. 1153, 25 L.Ed.2d 491 (1970); Baker v. Matheson, Utah, 607 P.2d 233 (1979); Purdie v. University of Utah, Utah, 584 P.2d 831 (1978). Since the Board of Regents may legitimately distinguish between residents and nonresidents by charging the latter a higher tuition, and may also impose a one-year residency requirement to assist in making that distinction, see Starns v. Malkerson, supra, at 236-37, the issue is whether the state, in determining whether the one-year requirement has been met, may rationally distinguish between students who reside outside the state for a period of more than thirty days during the one year, and those who do not.
*1164Appellants contend that their education-related research and temporary employment are legitimate reasons for extended absences from the state, and that it is “unfair [and] totally illogical to strip all persons who leave the state for more than thirty days of resident student status.” The argument is not valid. It is not the thirty-day absence rule that precludes residency status; it is appellants’ failure to rebut the presumption of nonresidency arising from a failure to establish physical presence in the state for one year (less a thirty-day grace period).
Under Rules I.A. and I.D., appellants’ motivation for leaving the state each summer is immaterial. Although motivation may be relevant in determining residency or domiciliary status in a different context, the purpose of the instant rules is to distinguish between those whose attachment to the state is sufficient to justify charging resident tuition and those who have a lesser detachment and are therefore less likely to contribute to their tax-subsidized education by the payment of taxes. In establishing general rules for distinguishing between residents and nonresidents for tuition purposes, the state must be reasonable in the classifications created by the rules. The classifications in this case rationally distinguish between those who come to this state solely for attendance at an institution of higher learning during the school year, and those who come with the intention of residing here for purposes other than enrolling at a state educational institution for an indefinite period of time.
The authority to draw lines that discriminate is neeessary if government is to act in the many areas of human conduct where the shades of human activity do not lend themselves to precise categories. When some legislative line must be drawn, it is no objection to the rule that some cases will fall closer to the line than others and thus may individually have more merit and greater claim to being treated differently than those that fall farther away. That objection will exist in virtually all cases. Such a determination provides no basis for holding a rule unconstitutional, as long as the classifications are reasonable. Baker v. Matheson, supra.7 The classification in this case is rationally based and imposes no invidious discrimination, even though the lines drawn by the rules may traverse gray areas. See generally Weinberger v. Salfi, 422 U.S. 749, 95 S.Ct. 2457, 45 L.Ed.2d 522 (1975); Dandridge v. Williams, 397 U.S. 471, 90 S.Ct. 1153, 25 L.Ed.2d 491 (1970).
Appellants would also have us alter the thirty-day rule to allow tacking of twelve nonconsecutive months of residency. This Court has no such power. The prerogative and power to draw such lines belongs to bodies invested with the power to legislate or to make rules under legislative authority.
In sum, the thirty-day rule as written does not unlawfully discriminate and is not unconstitutional.
B.
Appellants also contend that the University’s reliance on “nontemporary” employment and the purchase of property in Utah, as indicia of intent to establish permanent domicile, is a violation of equal protection. These two factors are among several set forth in Rule I.E. of the Board of Regents’ rules. See footnote 4. The specific issue here is whether these factors are reasonably indicative of domiciliary intent.
Appellants cite Kelm v. Carlson, 473 F.2d 1267 (6th Cir.1973), to support their argument that nontemporary employment may not be considered in determining domiciliary intent. Kelm invalidated a university regulation that required acceptance of post-graduate employment within the state in order to acquire resident-student status. Under the rules in the instant case, acceptance of nontemporary employment, before or after graduation, is not a requirement for resident status, but only one of several *1165criteria to be considered in determining “personal intent to remain indefinitely.” Rule I.E., footnote 4, su-pra.
Both employment and acquisition of property may provide some evidence of intent to remain indefinitely. Of course, a student with no actual intent to establish residency might purchase a home and obtain apparent permanent employment. Since, however, such actions are not likely taken solely to establish resident-status for tuition purposes, those factors have traditionally been used in determining whether one has an attachment to the state that is indefinite in duration and hence indicative of domiciliary intent. See, e.g., Vlandis v. Kline, supra, 412 U.S. at 454, 95 S.Ct. at 2237; Lister v. Hoover, 655 F.2d 123, 126 (7th Cir.1981); Hasse v. Board of Regents, 363 F.Supp. 677, 679 n. 3 (D.Hawaii 1973); Podgor v. Indiana University, 178 Ind.App. 245, 381 N.E.2d 1274, 1279-80 n. 2 (1978).
The Equal Protection Clause, in the circumstances of this case, requires only that similarly situated persons be treated similarly and that any differences in treatment be reasonably and fairly related to a legitimate governmental purpose. See Weinberger v. Salfi, supra; Dandridge v. Williams, supra; Baker v. Matheson, supra. Reliance upon employment and acquisition of property as evidence of one’s intent to establish a domicile is not unreasonably related to the purpose of the statute.
IV. REASONABLENESS OF THE UNIVERSITY’S RULING
Finally, appellants argue that the decision of the Residency Appeals Committee denying them resident status was arbitrary and capricious. Both parties agree that our scope of review is whether the University acted arbitrarily or capriciously. Since neither party disputes that proposition, we shall assume that to be the proper scope of review.
The Committee’s decision was supported by substantial evidence.8 Appellants first came to Utah in 1972, left in 1973, and returned in 1978, when they again enrolled as students at Utah State University. They applied for resident status in September, 1978, but clearly had not satisfied the one-year residency rule because of their sojourn of six years in Africa, followed by a summer of travel throughout this country. During the summer of 1978, George Frame held a New Jersey driver’s license. When they reapplied in April, 1979, they still had not satisfied the one-year residency requirement and did not establish that this state constituted their domicile. The Cache County clerk’s office had no record of appellants’ having registered to vote or having voted by absentee ballot, as claimed in their application. When out of state, they gave as *1166their permanent address the Department of Wildlife Science. They did not have a Utah driver’s license or car registered in their name in this state, and there is no record that they had ever filed Utah State income tax returns.9 It may be that the Committee could have ruled the other way, as the dissent contends it should have, but the ruling was not arbitrary or capricious.10
Affirmed. No costs.
HALL, C.J., and OAKS, J., concur.. In some contexts the terms residence and domicile have different meanings, but for the purpose of this opinion we will treat them synonymously.
. During the summer of 1979 appellants again left Utah to travel through other parts of the country in furtherance of their employment as free lance writers and photographers. They planned to return to Utah in September, 1979.
. Subsection (7) of § 53-34-2.2 states:
The board of regents after consultation with the institutions of higher education shall make rules and regulations, not inconsistent with the provisions of this section, concerning the definition of resident and nonresident students and establishing procedures for classifying and reclassifying students and criteria for judging claims of residency, domicile, emancipation, abandonment and other matters related to this section.
. Rule I.E. describes the type of evidence relevant to a determination of residency. It states:
An applicant for resident status must furnish evidence of personal intent to remain indefinitely by establishing significant legal and *1162other ties or contacts within the State of Utah during the year’s required residence, and by terminating reasonably terminable ties out of state. Significant ties and contacts may include, among other matters, the purchase of property; acceptance of non-temporary employment; establishment of banking relationships; qualification for Utah driver’s license; registration of a motor vehicle; registration to vote; membership and participation in off-campus political, social, religious, fraternal and civic associations; marriage to a Utah resident; or the existence of compelling nonacademic reasons for coming to Utah and leaving the previous domicile, such as health needs, divorce, or offer of permanent employment. The following factors may be grounds for denying resident status:
1. Out-of-state voter registration
2. Out-of-state motor vehicle registration
3. Out-of-state driver’s license
4. Out-of-state support to such an extent that the student would probably have to leave the
State of Utah if that support were withheld. [Emphasis added.]
.Rule I.C. states:
Motivation
The law presumes temporary academic motivation, and thus lack of domiciliary intent, in the case of persons who within a year after entering Utah from out of state, enroll in an institution of higher education in this state. This presumption is reinforced if the student has applied to a Utah college or university from an out-of-state address or immediately after entering the state and the entry into the state shortly precedes or coincides with the commencement of a school term. It is the student’s obligation to rebut this presumption in order to qualify for resident status. A student who clearly demonstrates that the move to Utah was not academically motivated, but was for permanent domiciliary reasons, is entitled to immediate resident status.
. The rationale of Vlandis v. Kline, 412 U.S. 441, 93 S.Ct. 2230, 37 L.Ed.2d 63 (1973), was limited in Weinberger v. Salfi, 422 U.S. 749, 95 S.Ct. 2457, 45 L.Ed.2d 522 (1975), which upheld a rule requiring spouses to be married for nine months before a widowed spouse could claim social security benefits based on the marriage. The court upheld the time limitation and held that a factual determination into the bona fides of the marriage need not be undertaken in each case to determine eligibility for social security benefits. Salfi rejected the requirement in Vlandis that legislatively-created irrebuttable presumptions must be "necessarily or universally true in fact,” id. at 768, 95 S.Ct. at 2468, and limited Vlandis "to those situations in which a State ‘purport[s] to be concerned with- [domicile, but] at the same time den[ies] to one seeking to meet its test of [domicile] the opportunity to show factors clearly bearing on that issue,’ ” Elkins v. Moreno, 435 U.S. 647, 660, 98 S.Ct. 1338, 1346, 55 L.Ed.2d 614 (1978), quoting Salfi, 422 U.S. at 771, 95 S.Ct. at 2469. Salfi follows traditional equal protection analysis in dealing with a rule of law based on a factual assumption that may be false in a given case. In Salfi, the Court stated:
[T]he benefits here are available upon compliance with an objective criterion, one which the Legislature considered to bear a sufficiently close nexus with underlying policy objectives to be used as the test for eligibility. Like the plaintiffs in Starns [v. Malkerson, appellants] are completely free to present evidence that they meet the specified requirements; failing in this effort, their only constitutional claim is that the test they cannot meet is not so rationally related to a legitimate legislative objective that it can be used to deprive them of benefits available to those who do satisfy that test.
Salfi at 772, 95 S.Ct. at 2470.
. We do not deal here with strict scrutiny cases.
. The University cited the following reasons for the ruling that the appellants had not met the objective test of Section E of the regents’ rule:
It would also appear that they had not met the requirement of showing objective evidence of intent to remain as described in Section E of the Rules and Regulations such as purchasing property, acceptance of non-temporary employment, or other evidences that would be of a nature to show that they in fact intended to remain in the State after graduation.
... While in Utah, the Frames gave their residence address as the home of a professor who was out of town. It was therefore assumed that that was a temporary residence for the Frames. They gave as their permanent address the Department of Wildlife Science, Utah State University. Therefore, Mr. Sorenson saw no permanent residence ties to the State other than the University, which was for academic purposes. The Cache County Clerk’s Office had no record of them being registered to vote or voting absentee as they claimed in their residency application. They also did not have a Utah drivers license nor a car registered in the State. When not enrolled at the University, Mr. Frame was doing research, lecturing, and consulting in Tanzania, Kenya, California, New Jersey, Pennsylvania, Washington, D.C., and New York, and he had not resided in the State for one continuous year at the time of their application. They had periodic absences from the State, usually in the amount of more than 30 days, which negated continuity in the State. Also, there was not [a] record that Mr. and Mrs. Frame had ever filed a Utah State Income Tax Return.
. See footnote 8, supra.
. The main thrust of the dissent is that the regents’ rules depart from § 53-34-2.2, the statute which authorizes the rules. We have not addressed that issue because neither party has raised it. Accordingly, the issue is not before the Court.