Correct Option (C)
For the hour and minute hands of a clock to coincide again, the minute hand must gain 360 degrees over the hour hand. The speeds of the hands are:
- Minute hand: 6 degrees per minute (360 degrees / 60 minutes).
- Hour hand: 0.5 degrees per minute (360 degrees / 12 hours / 60 minutes).
The relative speed of the minute hand with respect to the hour hand is 6 - 0.5 = 5.5 degrees per minute.
The time taken for the minute hand to gain 360 degrees over the hour hand is calculated as:
Time = Total angle to gain / Relative speed
Time = 360 degrees / 5.5 degrees/minute = 360 / (11/2) minutes = 360 × (2/11) minutes.
This calculation yields approximately 65.45 minutes. When rounded to the nearest integer, the time is 65 minutes.
Incorrect Options:
Options A (60 minutes), B (62 minutes), and D (67 minutes) are incorrect because the precise interval between consecutive coincidences of the hour and minute hands is approximately 65.45 minutes. An interval of exactly 60 minutes would imply the minute hand gains 360 degrees over a stationary hour hand, which is not the case. The calculated value of 65.45 minutes is closest to 65 minutes when rounded to the nearest integer, rendering the other options inaccurate.