Problem: At 2:152:152:15 o′'′clock, the hour and minute dials of a clock form an angle of:
Answer Choices:
A. 30∘30^{\circ}30∘
B. 5∘5^{\circ}5∘
C. 2212∘22 \dfrac{1}{2}^{\circ}2221∘
D. 712∘7 \dfrac{1}{2}^{\circ}721∘
E. 28∘28^{\circ}28∘
Solution:
In 151515 minutes the hour hand moves through an angle of 14\dfrac{1}{4}41 of 30∘=712∘30^{\circ}=7 \dfrac{1}{2}^{\circ}30∘=721∘. Therefore, the angle between the hour hand and the minute hand is 2212∘22 \dfrac{1}{2}^{\circ}2221∘.