At what time between 2 and 3 will the hour and minute hands of a clock

At what time between 2 and 3 will the hour and minute hands of a clock be 12 minutes divisions apart ?

20 minutes past 2
24 5/11 minutes past 2
24 minutes past 2
24 12/13 minutes past 2
This question was previously asked in
UPSC CAPF – 2015
The hour and minute hands of a clock will be 12 minutes divisions apart at 24 minutes past 2.
12 minute divisions on a clock correspond to an angle of 12 * 6 = 72 degrees (since there are 60 minute divisions in 360 degrees, so each division is 6 degrees).

At 2:00, the hour hand is at the 2 o’clock mark (10 minute divisions or 60 degrees from 12), and the minute hand is at the 12 o’clock mark (0 degrees). The angle between them is 60 degrees, with the hour hand ahead of the minute hand.

The minute hand moves at 6 degrees per minute, and the hour hand moves at 0.5 degrees per minute. The relative speed of the minute hand with respect to the hour hand is 6 – 0.5 = 5.5 degrees per minute.

Let ‘t’ be the number of minutes past 2 when the hands are 72 degrees apart.
At time ‘t’, the angle of the minute hand from 12 is 6t degrees.
At time ‘t’, the angle of the hour hand from 12 is (60 + 0.5t) degrees.

We want the absolute difference between these angles to be 72 degrees:
|6t – (60 + 0.5t)| = 72
|5.5t – 60| = 72

Two possible cases:
1) 5.5t – 60 = 72
5.5t = 132
t = 132 / 5.5 = 1320 / 55 = 264 / 11 = 24 minutes.
This corresponds to the minute hand being ahead of the hour hand by 72 degrees.

2) 5.5t – 60 = -72
5.5t = -12
t = -12 / 5.5. This is a negative time, which is not applicable for the time between 2 and 3. This situation (hour hand 72 degrees ahead of minute hand) occurs before 2:00.

Therefore, the only time between 2 and 3 when the hands are 12 minute divisions (72 degrees) apart is exactly 24 minutes past 2.

Clock problems often involve the relative speed of the hands. The minute hand completes a full circle (360 degrees) in 60 minutes, while the hour hand completes a full circle in 12 hours (720 minutes). The relative speed of the minute hand is 5.5 degrees/minute (or 11/2 degrees/minute) faster than the hour hand. This relative speed is key to calculating when specific relative positions occur.
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