In defendant’s first assignment of error he objects to the patrolman’s testimony in which the patrolman explained the purpose for the center line on the highway. Defendant argues that the testimony amounts to a conclusion of law by a non-expert as to the effect and reason for the center line. It is argued the error is prejudicial in that it places before the jury evidence of guilt of an offense for which defendant had not been charged. We disagree.
At the point in the patrolman’s testimony where this evidence occurred, he was testifying as to why he, as a trained law enforcement officer, decided to stop defendant. The first reason given was that the defendant was driving at a rate of speed considerably in excess of the posted speed limit. The patrolman’s testimony as to defendant’s speed is competent and not challenged by the defendant on appeal. The second reason was that while travelling at a high rate of speed, defendant drove across the center line in the face of oncoming traffic, forcing the oncoming vehicle out of its lane and off the road. Defendant’s action indicates the operation of a motor vehicle in such a manner as to have actually placed another member of the motoring public in peril. This evidence was competent to show that the patrolman, trained in the enforcement of the traffic laws of this State, had reason to stop the defendant.
The fact that such evidence is also evidence of violations for which defendant was charged is of no moment. Evidence which tends to prove other offenses is competent where such evidence exhibits a chain of circumstances with respect to the offense in issue, and is so connected with the offense charged as to throw light upon one or more of the questions in issue. State v. Atkinson, 275 N.C. 288, 167 S.E. 2d 241 (1969). The patrolman’s testimony concerning defendant’s speeding and crossing the center line was competent to show the patrolman’s justification in pursuing and stopping the defendant.
 In his second assignment of error brought forward for argument, defendant contends that the trial court erred in allowing the patrolman and breathalyzer operator to testify as to their opinion concerning defendant’s state of intoxication. The prosecution asked each officer if he had an opinion satisfactory to himself as to whether the defendant was under the influence of intoxicating beverages. Each answered that in *373his opinion the defendant had consumed sufficient intoxicants so as to appreciably impair his mental and physical abilities. After giving the opinion, each officer stated the observations upon which the opinion was based, including the manner of vehicle operation, odor of alcohol, unsteadiness, and slurred speech.
Defendant argues that the officers, in stating their opinions, invaded the province of the jury by prejudicially offering conclusions on the very issue to be decided by the jury. He further contends that the jury was capable of drawing its own conclusion from the evidence to be gleaned from the officers’ observations and relation of facts. This argument is without merit. It is now “a familiar rule of evidence in this jurisdiction that a lay witness who has personally observed a person may give his opinion as to whether that person was under the influence of intoxicants.” State v. Lindley, 286 N.C. 255, 258, 210 S.E. 2d 207, 209 (1974); see, e.g., State v. Cook, 273 N.C. 377, 160 S.E. 2d 49 (1968); State v. Flinchem, 247 N.C. 118, 100 S.E. 2d 206 (1957); State v. Warren, 236 N.C. 358, 72 S.E. 2d 763 (1952); State v. Harris, 213 N.C. 648, 197 S.E. 142 (1938); State v. Buchanan, 22 N.C. App. 167, 205 S.E. 2d 782 (1974); and State v. Dark, 22 N.C. App. 566, 207 S.E. 2d 290 (1974).
 In his final assignment of error brought forward for argument, defendant contends the breathalyzer test results should have been suppressed. He cites State v. Shedding, 17 N.C. App. 279, 194 S.E. 2d 55 (1973), for the proposition that where a person is advised of his rights under G.S. 20-16.2 (a) and does not waive them, the results of the breathalyzer tests. are admissible only if the testing was delayed (not to exceed thirty minutes) to give the defendant an opportunity to exercise such rights.
The trial judge conducted a voir dire to determine the admissibility of the breathalyzer test results. In declaring the results admissible, he made findings of fact that the defendant was brought to the police station and advised of his rights under G.S. 20-16.2 (a) at 11:30 p.m.; that he understood his rights and had no questions; and that the test was administered at 11:55 p.m. Defendant contends that under the holding in Shadding, supra, since no waiver was made by defendant, the police had to wait thirty minutes before administering the *374test. Because they waited only twenty-five minutes, the police violated the prescribed procedure. We disagree.
General Statute 20-16.2 (a) states and Shadding so holds that the breathalyzer test will be delayed a maximum of thirty minutes from the time defendant is notified of his rights. The statute gives the defendant the right to have a lawyer, doctor, nurse, or witness present at the testing. The purpose of the delay is to allow the defendant, who exercises his rights, a reasonable but limited amount of time to procure their presence. The effect of the statute then is to require a defendant to exercise his rights in a timely manner. Even if he does exercise his rights within thirty minutes of notification, the test can and will be administered after the lapse of thirty minutes regardless of whether the requested persons have arrived.
Beyond the delay described above, there is no statutorily prescribed delay. In the present case there was a period of twenty-five minutes after notification during which defendant made no effort to exercise his rights. At the time the test was administered, defendant made no effort to exercise his rights. The police are not required' to delay testing unless the defendant exercises his rights. Thus there was no error in the testing procedures nor in the admission of the test results.
Judges Vaughn and Clark concur.