Aptitude - Clock - Discussion

Discussion Forum : Clock - General Questions (Q.No. 17)
17.
How many times do the hands of a clock coincide in a day?
20
21
22
24
Answer: Option
Explanation:

The hands of a clock coincide 11 times in every 12 hours (Since between 11 and 1, they coincide only once, i.e., at 12 o'clock).

AM

12:00
1:05
2:11
3:16
4:22
5:27
6:33
7:38
8:44
9:49
10:55

PM

12:00
1:05
2:11
3:16
4:22
5:27
6:33
7:38
8:44
9:49
10:55

The hands overlap about every 65 minutes, not every 60 minutes.

The hands coincide 22 times in a day.

Discussion:
11 comments Page 2 of 2.

Anurag Nayak said:   1 decade ago
Reference time let suppose..12 o clock
we know 6t=.5t+theta
at 12 theta = 0
so next time the clock will coincide at
6t= .5t + 360
t= 65*5/11
so after every 65*5/11 min..the clock will coincide ..
in a day there is 1440 min..
so the number of times that the both hands will coincide is:
=1440/[720/11]
=22


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