How many times do the hands of a clock coincide in 5 hours ?

A. 5

B. 4

C. 6

D. 3

Answer : B. 4

Explanation:

Hour hand and minute hand coincide every 65:5 minute, so in 5 hour they will coincide 4 times The hour hand covers 2*360 degrees in 24 hours, i.e 1440 minutes. So, in one minute, it covers 1440/720 = 1/2 degree.

Difference in angular distance travelled by the minute hand and the hour hand in one minute is thus 6-1/2 = 11/2 degrees. So, on a full rotation (360), any similar event between them will be repeated every 360/(11/2) = 65 5/11 minutes.

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