Discussion Forum



1)

The hands of a clock coincide after every 66 min. of correct time. How much is the clock fast or slow in 24 hours?


A) 11(109/121) min slow

B) 11(110/121) min. slow

C) 11(13/65) min slow

D) 11(45/80) min slow

E) 10(109/121) min .slow

Answer:

Option A

Explanation:

In a correct clock, the minute hand gains 55 min. spaces over the hour hand in 60 min.
To be together again the clock must gain 60 min. over the hour hand.
55 min. are gained in 60 min.

6-0 min. are gained in (60/55) x 60 = 65(5/11) min.

But they are together after 66 min.

Lose in 66 min. = 66-(65(5/11))=(6/11).

Lose in 24 hours =[ (6/11) x ((60 x 24)/66)] min = 1440/121 = 11(109/121).

There for, the clock is slow by 11(109/121) min