The defendant excepted to the admission in evidence of the plaintiff’s statement that the speed limit at the time and place of the accident was thirty-five miles per hour and to those portions of the charge based upon that evidence. These exceptions are the bases of defendant’s assignments of error Nos. 2, 3, 18, 19 and 20.
In her specifications of negligence plaintiff alleged that defendant Wallen was operating his automobile at a speed which was excessive under the existing conditions in violation of G.S. 20-141 (a). She made no other allegation with reference to his speed. She did not allege that *677the approach to the scene of the collision was either a business or a residential district or that the proper authorities had posted any signs giving notice of any determined speed limit for the area. Thus G.S. 20-141 (a) and (b)4 were pertinent in judging the conduct of the defendant. Bobbitt v. Haynes, 231 N.C. 373, 57 S.E. 2d 361.
In answer to a question from her counsel as to whether there had been any changes in highway conditions at the scene of the collision since the accident, plaintiff said, “Yes, the speed limit has been changed. It was 35 at the time and now it is 45.” The defendant’s motion to strike this answer was denied.
It is noted that plaintiff did not say there was a posted sign in the area limiting speed to thirty-five miles per hour. She merely said the speed limit “was 35.” This statement constituted the only evidence in the record from which the jury might have found that the law had fixed a maximum speed limit of less than fifty-five miles per hour on Patton Avenue. No inference of a lesser limit arises from the fact that the collision occurred in the city limits. The record is silent as to whether the area constituted a business or a residential district as defined by the statute.
In his recapitulation of the evidence the judge told the jury that plaintiff said thirty-five miles per hour was the posted speed limit on Patton Avenue at that point at that time and, in stating the contentions, he said that plaintiff contended that defendant was driving fifty miles per hour “when the posted maximum speed out there was 35 miles per hour.” Thereafter he gave the following mandate:
“The court instructs you that if the plaintiff has satisfied the jury from the evidence in this case, and by its greater weight, that the maximum lawful speed at the point of collision was 35 miles per hour, and that Wallen was driving at a speed in excess of the maximum lawful speed limit, or that regardless of the speed limit that Wallen was driving at a speed which was greater than was reasonable and prudent under the condition then existing, and has further satisfied you by the greater weight of the evidence that his driving in either of those respects was the proximate cause, or one of the proximate causes of the collision which ensued, and of the injuries which she sustained, then that would amount in law to actionable negligence on the part of William M. Wallen, and it would be your duty to answer the first issue YES.”
In our opinion the admission of this evidence and the charge with reference to it constituted prejudicial error.
Over objection, a witness may not testify what the maximum speed *678permitted by law is for a given area. What is the speed limit is a mixed question oí fact and law, except where the State Highway Commission or local authorities, pursuant to the statute, have determined a reasonable and safe speed for a particular area and have declared it by erecting appropriate signs. The answer to the question, “What is the maximum speed permitted by law for a given area?” depends upon whether that area is a business or residential district as defined by G.S. 20-38 (a) and (w)l, or “places other than those,” G.S. 20-141(b) 4. In the absence of a stipulation, it is necessary to prove the character of the district before the maximum speed permitted by law can be determined. Frequently the nature of a particular district cannot be satisfactorily proven without detailed measurements of the buildings fronting the highway for the required distance. To permit a witness to say what a speed limit was for a particular area at a given time is to allow him to give his inferences from facts which he has observed. Such testimony violates the opinion rule and invades the province of the jury. Mason v. Gillikin, 256 N.C. 527, 124 S.E. 2d 537; Stansbury, North Carolina Evidence, Secs. 122 and 123. Of course, if a highway sign declaring the speed limit to be thirty-five miles per hour had been posted in the area, it would have been competent for the witness to say so, describe the sign, and testify as to its location. When such a sign is present, nothing else appearing, there is a logical inference that it was erected by the proper authorities pursuant to G.S. 20-141. Smith v. Buie, 243 N.C. 209, 90 S.E. 2d 514.
There was neither allegation nor competent evidence upon which the jury might find that the maximum legal speed for Patton Avenue in the area in question was thirty-five miles per hour. There was no evidence that defendant was exceeding fifty-five miles per hour. Therefore, the prejudicial effect of that portion of the quoted charge is apparent. Brady v. Beverage Co., 242 N.C. 32, 86 S.E. 2d 901.
The defendant makes several assignments of error to the charge with reference to the issue of plaintiff’s ownership of the Hensley automobile. However, the jury’s finding that the operator, the additional-defendant, was not negligent renders these assignments moot on this appeal. These and the other assignments of error relate to matters which may not reoccur upon another trial.
For the reasons stated the defendant is entitled to a new trial, it is so ordered.
New trial.