A plaintiff sued a defendant for injuries the plaintiff received in an automobile accident. The plaintiff claims the defendant was negligent in (a) exceeding the posted speed limit of 35 m.p.h., (b) failing to keep a lookout, and (c) crossing the center line. The defendant testified in his own behalf that he was going 30 m.p.h. On cross-examination, the plaintiff's counsel did not question the defendant with regard to his speed. Subsequently, the plaintiff's counsel calls a police officer to testify that, in his investigation following the accident, the defendant told him he was driving 40 m.p.h. The officer's testimony is
