J. H. Harvey Company (“Harvey”) appeals from the trial court’s denial of its motion for summary judgment in this slip-and-fall premises liability case. Harvey also appeals the trial court’s denial of its motion to strike and objections to plaintiff Carolyn Reddick’s deposition errata sheet. For reasons that follow, we affirm.
*4671. The standard of review applicable to motions for summary judgment is well established:
To prevail at summary judgment under OCGA § 9-11-56, the moving party must demonstrate that there is no genuine issue of material fact and that the undisputed facts, viewed in the light most favorable to the nonmoving party, warrant judgment as a matter of law.
Lau’s Corp. v. Haskins, 261 Ga. 491 (405 SE2d 474) (1991). Moreover, with respect to slip-and-fall cases, we are reminded by the Supreme Court that
the “routine” issues of premises liability, i.e., the negligence of the defendant and the plaintiff, and the plaintiff’s lack of ordinary care for personal safety are generally not susceptible of summary adjudication, and that summary judgment is granted only when the evidence is plain, palpable, and undisputed.
Robinson v. Kroger Co., 268 Ga. 735, 748 (493 SE2d 403) (1997).
Viewed in the light most favorable to Reddick, the evidence shows as follows. At approximately 5:55 p.m. on September 5, 1996, Reddick slipped and fell while shopping in a Harvey grocery store in Americus. Reddick was walking down an aisle displaying bread on one side and frozen foods on the other when her right foot slipped on “something slippery,” causing her to fall forward onto her knees. As she was getting up, Reddick saw two scuppernongs1 on the floor to her left. Reddick does not know whether she actually stepped on the scuppernongs, does not recall whether they were whole or squashed flat, and does not know if they caused her to fall. Reddick does not recall seeing anything else on the floor that might have caused her to fall, and she does not remember seeing any substance on the knees of her slacks after she got up. Reddick assumed, however, that the scuppernongs caused her to fall because she noticed them on the floor near her after she fell.
After Reddick got up, she reported the incident to the store’s assistant manager, Bruce Jones. Reddick and Jones returned to the aisle where Reddick had fallen, and Jones saw two scuppernong skins on the floor. According to Jones, scuppernongs are generally located in the produce department, several aisles away, and one *468would not expect to find them in the aisle where Reddick fell. After examining the area, Jones completed an accident report in which he stated that “[a]n unknown customer was apparently eating scuppernongs and threw the outer skin on the floor. (2 scuppernongs). [Red-dick] walked around the corner next to the bread and said she slipped and fell on her knees.” During his deposition, Jones explained that in the past, customers at the store had eaten scuppernongs and thrown them on the floor. A former Harvey employee, Reginald Adams, testified by affidavit that the Americus store “had problems with items on the floor. These problems included customers eating items in the store and then throwing the items on the floor.”
Harvey filed a motion for summary judgment, and the trial court denied it. We then granted Harvey’s application for interlocutory appeal.
To prove negligence in a foreign substance slip-and-fall case, the plaintiff must show “(1) that the defendant had actual or constructive knowledge of the foreign substance and (2) that the plaintiff was without knowledge of the substance or for some reason attributable to the defendant was prevented from discovering the foreign substance.” (Punctuation omitted.) Robinson, supra at 736. Harvey maintains that it is entitled to summary judgment on several grounds, each of which we reject.
(a) First, Harvey argues that Reddick failed to present any evidence that her fall was caused by the scuppernongs on the floor of the store. To survive summary judgment, a slip-and-fall plaintiff “must introduce evidence which affords a reasonable basis for the conclusion that it is more likely than not that the conduct of the defendant was a cause in fact of the result.” (Punctuation omitted.) Christopher v. Donna’s Country Store, 236 Ga. App. 219, 220 (1) (511 SE2d 579) (1999). Reddick admitted during her deposition that she did not know what caused her to fall, but stated that she assumed the scuppernongs were responsible. Citing Hall v. Cracker Barrel &c., 223 Ga. App. 88 (476 SE2d 789) (1996), Harvey contends that Reddick’s testimony demonstrates the absence of causation in this case. We disagree.
In Hall, the plaintiff slipped and fell on wood flooring which she described as “slippery.” Id. at 88. Although she alleged that the floor was excessively waxy, the plaintiff failed to present any evidence of a foreign substance on the floor which could have created a slippery condition. Likewise, the plaintiff failed to show that the defendant improperly cleaned or maintained the floors. We concluded that the plaintiff’s bare assertion that the floor was “slippery,” without more, was insufficient to create an issue of fact as to whether the fall was caused by the defendant’s negligence. Id. at 93. We noted that “proof of nothing more than the occurrence of the fall is insufficient to *469establish the proprietor’s negligence.” (Punctuation omitted.) Id. at 90.
In this case, by contrast, Reddick has presented evidence of a foreign substance — two scuppernongs on the floor in the area where she fell — that could have created the slippery condition she alleged. We are required on a motion for summary judgment to view the facts and inferences in a light most favorable to Reddick. See Lau’s Corp., supra. Although Reddick could not positively state that the scuppernongs caused her to fall, reasonable jurors could make such an inference based on the proximity of the fruit to Reddick after the fall, the alleged “slipper/’ condition of the floor, and the assistant manager’s statement after Reddick’s fall that he saw scuppernong skins, rather than whole fruit. See Williams v. EMRO Marketing Co., 229 Ga. App. 468, 472 (2) (494 SE2d 218) (1997) (Ruffin, J., concurring specially) (evidence permitted reasonable inference that plaintiff slipped and fell on ice even though plaintiff did not see what he slipped on).
(b) Second, Harvey contends that Reddick failed to prove that it had actual or constructive knowledge of the presence of the scuppernongs on the floor. Reddick argues that Harvey had both actual and constructive knowledge of the hazard. We find no evidence of actual knowledge, but agree with Reddick that there are factual disputes concerning Harve/s constructive knowledge.
Reddick’s actual knowledge argument is based on (1) Jones’ deposition testimony that customers previously had eaten scuppernongs and thrown them on the floor and (2) the affidavit of former Harve/s employee Reginald Adams that the store had a problem with customers throwing food on the floor. To establish actual knowledge, however, Reddick must do more than merely show that Harvey’s employees had a general knowledge that a hazardous condition might exist. See J. H. Harvey Co. v. Johnson, 211 Ga. App. 809, 810 (440 SE2d 548) (1994) (“although management had knowledge of the periodic defrosting of the meat cooler, the record does not show that any employee or manager of the supermarket had actual knowledge of the alleged water leakage onto the floor prior to Johnson’s fall”), overruled in part on other grounds, Robinson, supra. Here, Jones testified merely that customers had thrown scuppernongs on the floor in the past. There is no evidence concerning the date or frequency of such incidents and no evidence that Jones had actual knowledge of any customers throwing food on the floor on the day that Reddick fell. Adams averred only that the store had “problems with items on the floor . . . including] customers eating items in the store and then throwing the items on the floor.” Adams did not state that he was aware of scuppernongs on the floor on the dáy of Reddick’s fall, or even that he was working in the store that day. This evidence is not sufficient to establish Harve/s actual knowledge of the hazard.
*470Reddick also maintains that Harvey had constructive knowledge of the hazard. Constructive knowledge can be proven by showing either (1) “that an employee of the proprietor was in the immediate area of the hazardous condition and could have easily seen the substance” or (2) “that a foreign substance remained on the floor for such a time that ordinary diligence by the proprietor should have effected its discovery.” (Punctuation omitted.) Brown v. Piggly Wiggly Southern, 228 Ga. App. 629, 631 (3) (b) (493 SE2d 196) (1997). As Reddick testified that she did not see any Harvey employees around when she fell, and there was no other evidence of store employees in her immediate vicinity, she must use the second method of proving constructive knowledge. To withstand a motion for summary judgment using that method, “a plaintiff need not show how long a substance has been on the floor unless the defendant has established that reasonable inspection procedures were in place and followed at the time of the incident.” Straughter v. J. H. Harvey Co., 232 Ga. App. 29, 30 (1) (500 SE2d 353) (1998) (whole court). Thus, we must determine whether Harvey has established that it had in place a reasonable inspection procedure which it was following on the afternoon of Red-dick’s fall.
Harvey presented evidence that, at the time of Reddick’s fall, the Americus store had an inspection policy requiring that the floor be swept and spot mopped at least every two hours, or more often as needed. The sweeping included spot mopping to remove foreign substances from the floor. Employees were required to punch in and out on a “sweep card” when beginning and ending the sweep and to initial the card upon completion. Harvey also submitted the affidavit of employee Brad Satterfield, who averred that on the day Reddick fell he swept the entire floor area of the store from 3:25 p.m. until 4:14 p.m., and again from 5:17 p.m. until 6:01 p.m., as indicated on the relevant sweep card. Satterfield testified that he swept the aisle where Reddick fell approximately one hour and forty-two minutes before her fall and found no trash, debris, or liquid in the area. Finally, Harvey submitted the sweep card for the week of Reddick’s fall, which bears Satterfield’s initials beside two punched entries on the day in question recording time “in a type of military time with minutes reflected in hundredths of an hour.” In the absence of any evidence to the contrary, the sweep card, coupled with the testimony of Jones and Satterfield, establishes that the area where Reddick fell was swept one hour and forty-two minutes prior to her fall, and that no foreign substance was found.2
*471We cannot conclude as a matter of law, however, that Harvey’s inspection procedure was reasonable under the circumstances. The length of time that a foreign substance must remain on the floor before a proprietor should have discovered it — and, by extension, what constitutes a reasonable frequency of inspections — “will vary with the circumstances of each case (the nature of the business, size of the store, the number of customers, the nature of the dangerous condition and the store’s location).” (Punctuation omitted.) Kelley v. Piggly Wiggly Southern, 230 Ga. App. 508, 510 (2) (496 SE2d 732) (1998). In cases where a proprietor has shown that an inspection occurred within a brief period prior to an invitee’s fall, we have held that the inspection procedure was adequate as a matter of law. See, e.g., Deloach v. Food Lion, 228 Ga. App. 393, 394-395 (491 SE2d 845) (1997) (area where plaintiff fell was inspected ten minutes prior to fall, establishing reasonable care as a matter of law); Jenkins v. Bi-Lo, 223 Ga. App. 735, 736-737 (479 SE2d 14) (1996) (same); Super Discount Markets v. Clark, 213 Ga. App. 132, 133 (443 SE2d 876) (1994) (inspection occurred fifteen to twenty minutes prior to incident). Here, the floor had not been swept or inspected for one hour and forty-two minutes before Reddick fell, and the scuppernongs could have remained on the floor that long. There also was testimony that Harvey was aware that customers occasionally ate food — including scuppernongs — and threw the residue on the floor, and that the floor was brown and could camouflage dropped or spilled food. Moreover, Jones admitted during his deposition that one hour and forty-two minutes was “too long for a substance to be on the floor.” Under these circumstances, we conclude that the reasonableness of Harvey’s inspection and cleaning procedures is a question for the jury and that Harvey was not entitled to summary judgment on the issue of constructive knowledge. See Jones v. Krystal Co., 231 Ga. App. 102, 104-105 (d) (498 SE2d 565) (1998) (failure to inspect floor of fast food restaurant for twenty minutes or longer could be unreasonable); Smith v. Toys “R” Us, 233 Ga. App. 188, 191-192 (1) (504 SE2d 31) (1998) (failure to inspect store entrance area during period of one hour and thirty minutes gave rise to jury question on reasonableness of inspection procedures).
(c) Harvey also sought summary judgment on the ground that Reddick failed to exercise ordinary care for her own safety. Reddick *472testified that she did not look down at the floor before she fell. She also testified that the fruit on which she allegedly slipped was large and could have been as big in diameter as a soda can. Harvey argues that this evidence establishes that had she been exercising ordinary care for her own safety, Reddick would have noticed the fruit before she fell. However, this, too, is a jury question.
In Robinson, the Supreme Court rejected the argument that “an invitee fails to exercise ordinary care for personal safety as a matter of law when the invitee admits she failed to look at the location where she subsequently placed her foot.” Id. at 743. An invitee is not required to maintain a constant lookout, but “is entitled to assume that the owner/occupier has exercised reasonable care to make the premises safe.” Id. Accordingly, Reddick’s failure to look before she stepped does not establish negligence on her part as a matter of law. Additionally, contrary to Harvey’s assertions, the evidence does not establish conclusively that Reddick would have noticed the fruit had she glanced down. The size of the scuppernongs is a matter of dispute, as Jones testified that they were approximately the size of a quarter. Moreover, the evidence showed that the color of the floor could have camouflaged the scuppernongs. Under these circumstances, Harvey is not entitled to summary judgment on this issue. See Kroger Co. v. Brooks, 231 Ga. App. 650, 656 (2) (500 SE2d 391) (1998).
2. In its second enumeration of error, Harvey contends that the trial court erred in denying its motion to strike and objections to Red-dick’s substantive changes to her deposition. We find no error.3
After giving her deposition, Reddick submitted an errata sheet listing 16 changes to answers in her deposition transcript. Most of the changes substantively altered her testimony as previously recorded on material issues in the case, but did not clearly contradict it. For example, Harvey’s attorney asked Reddick during her deposition about the size of the fruit on which she allegedly slipped, as follows: “Q. We have got a 7-Up can on the table. Were they the size of that 7-Up can, that big around? A. Yes, they were. If I can remember, as far as my knowledge, when I was getting up, they was large red plums.” On her errata sheet, Reddick changed her answer to “[t]hey were regular size plums” and gave as the reason for the change, “I did not understand the question.” This change is consistent with her answer to a previous question that the plums were “regular” in size. As another example, Reddick replied, “I don’t know,” when asked in *473her deposition whether she had reached a conclusion about what caused her to fall, but in her errata sheet she changed this answer to “[sjomething slippery on the floor,” citing confusion about the question as the reason for the change. The new answer on the errata sheet is consistent with other testimony in Reddick’s deposition in which she attributed her fall to a “slippery” substance on the floor. Harvey filed a motion to strike and objections to the errata sheet, arguing that Reddick could not substantively change her deposition testimony because her lawyer did not object to the questions posed to Reddick at the deposition.
OCGA § 9-11-30 (e) provides as follows:
If requested by the deponent or a party before completion of the deposition, the deponent shall have 30 days after being notified by the officer that the transcript or recording is available in which to review the transcript or recording and, if there are changes in form or substance, to sign a statement reciting such changes and the reasons given by the deponent for making them. The officer shall indicate in the certificate . . . whether any review was requested and, if so, shall append any changes made by the deponent during the period allowed.
(Emphasis supplied.) Although our Georgia courts have not directly addressed the question of whether a witness may make substantive, material changes to his deposition,4 the statute expressly contemplates changes to form or substance. In addition, federal courts which have addressed this issue have overwhelmingly concluded that a witness may make “any changes in form or substance which the witness desires, even if the changes contradict the original answers or even if the deponent’s reasons for making the changes are unconvincing.”5 (Citation and punctuation omitted.) Lugtig v. Thomas, 89 FRD 639, 641 (N.D. Ill. 1981); see also, e.g., Podell v. Citicorp Diners Club, 112 F3d 98, 103 (2nd Cir. 1997); Innovative Marketing &c. v. Norm Thompson Outfitters, 171 FRD 203, 204-205 (W.D. Tex. 1997); Allen & Co. v. Occidental Petroleum Corp., 49 FRD 337, 340 (S.D. N. Y. *4741970); Colin v. Thompson, 16 FRD 194, 195 (W.D. Mo. 1954). These decisions are based on the plain language of Federal Rule 30 (e), which is virtually identical to OCGA § 9-11-30 (e).
There are several important safeguards which curtail abuse on the part of the deponent. First, the deponent’s original answers remain part of the record and can be read at trial to impeach the witness or for further clarification. Scarbrough v. Dover Elevator Co., 232 Ga. App. 149, 153 (a), n. 5 (500 SE2d 616) (1998); Lugtig, supra at 641. This is because “a deposition is not a ‘take home examination’ and an ‘errata sheet’ will not eradicate the import of previous testimony taken under oath.” Rios v. Welch, 856 FSupp. 1499, 1502 (D. Kan. 1994), aff’d, Rios v. Bigler, 67 F3d 1543 (10th Cir. 1995). Second, if the changes are “so substantial as to cause the deposition to become incomplete or useless without further testimony,” then the examiner may reopen the deposition and propound further questions to the witness concerning the nature of and reason for the changes. Allen & Co., supra at 341; see also Lugtig, supra at 642. Finally, where the deponent is a party, his self-contradictory testimony must be construed against him and cannot create an issue of fact for the purpose of summary judgment unless the contradiction is adequately explained. See Prophecy Corp. v. Charles Rossignol, Inc., 256 Ga. 27, 28-29 (1) (343 SE2d 680) (1986).
Despite the plain language of OCGA § 9-11-30 (e), Harvey argues that a witness’ ability to change his deposition is limited by OCGA § 9-11-32 (d) (3) (B), which provides that
[e]rrors and irregularities occurring at the oral examination in the manner of taking the deposition, in the form of the questions or answers, . . . and errors of any kind which might be obviated, removed, or cured if promptly presented are waived unless seasonable objection thereto is made at the taking of the deposition.
According to Harvey, Reddick’s failure to understand the questions posed to her constituted an error or irregularity that could have been corrected during the deposition and was therefore waived. We disagree. First, we question whether a witness’ failure to understand a question is an “error or irregularity” within the meaning of OCGA § 9-11-32 (d) (3) (B). Georgia courts have interpreted deposition errors and irregularities to include such matters as failure of the attorney to object to the form of a question, Haynes v. McCambry, 203 Ga. App. 464, 468 (3) (416 SE2d 893) (1992); to the competency of the deponent to testify, Rigby v. Powell, 236 Ga. 687-688 (1) (225 SE2d 48) (1976); or to the videotaping of the deposition, DuBois v. Ray, 177 Ga. App. 349, 351-352 (1) (339 SE2d 605) (1985). Harvey cites no case *475holding that a witness’ failure to understand a question constitutes a deposition error or irregularity. Second, as a matter of common sense, the waiver provision of OCGA § 9-11-32 (d) (3) (B) can apply only to errors or irregularities which were known at the time of the deposition. Harvey asserts that Reddick must have known during the deposition that she did not understand the questions at issue, but this is not necessarily the case. Reddick may have thought that she understood the questions, but later realized upon reading them that, in fact, she did not. In light of the plain language of OCGA § 9-11-30 (e) permitting, without limitation, changes to form and substance, we decline to adopt Harvey’s strained interpretation of OCGA § 9-11-32 (d) (3) (B).
Applying these principles to the instant case, we find that Red-dick was entitled to make the changes to her deposition testimony. She reserved her right to read and sign her deposition transcript, apparently submitted her errata sheet in a timely manner, and provided explanations for the changes. See OCGA § 9-11-30 (e). Although her changes substantively alter her original deposition testimony, they do not clearly contradict it and therefore do not require application of the Prophecy rule described above.6 Under these circumstances, the trial court did not err in denying Harvey’s motion to strike and objections.
Judgment affirmed.
Johnson, C. J., McMurray, P. J., Pope, P. J., Smith and Eldridge, JJ, concur. Andrews, P. J., dissents.During her deposition, Reddick referred to the fruits she saw as plums, but in a subsequent affidavit, Reddick stated that she has since learned that they are called scuppernongs, which are large grapes. See Webster’s New Intl. Dictionary (2nd ed.), p. 2252.
Reddick contends that the sweep card is inadmissible hearsay that does not meet the requirements of the business records exception. We disagree. Jones testified that the sweep card for the week ending September 7,1996, was kept in the ordinary course of business and *471included all entries for the day of Reddick’s fall. Satterfield testified that he personally swept the floor twice that day, as reflected by the entries on the sweep card initialed by him. This evidence satisfies the foundational requirements of OCGA § 24-3-14 (b). See Mealor v. State, 233 Ga. App. 193, 194 (2) (504 SE2d 29) (1998) (explaining requirements); Peachtree North Apts. v. Arkhora Assoc., 140 Ga. App. 20, 21 (2) (230 SE2d 83) (1976) (testimony of corporate officer that time sheets were kept in normal course of business established admissibility).
For purposes of ruling on Reddick’s motion for summary judgment, we have considered only the original deposition transcript and not the errata sheet. Nevertheless, we address this issue in the event that the parties seek to make use of Reddick’s deposition on remand.
In Young v. YMCA of Metro. Atlanta, 204 Ga. App. 224 (419 SE2d 97) (1992), a slip- and-fall plaintiff testified at her deposition that she fell on a step because of the presence of soapy water, but later changed her testimony to indicate that she fell because the step was oversized. Although we noted in passing that the plaintiff’s errata sheet “is authorized by OCGA § 9-11-30 (e),” the central issue in Young was not the scope of the change, but whether the plaintiff properly submitted the errata sheet. Id. at 225.
Because Georgia’s Civil Practice Act is modeled on the Federal Rules of Civil Procedure, decisions of the federal courts interpreting the federal rules are persuasive authority. Ambler v. Archer, 230 Ga. 281, 287 (1) (196 SE2d 858) (1973).
In any event, Harvey does not seek to apply the Prophecy rule here, but only challenges Reddick’s right to make substantive changes to her deposition.