type 5 comparing clocks Detailed Explanation And More Example

Answer: (b)

After 12 days, i.e., after 12 × 24 hours clock A will gain 48 minutes and will show 12:48 noon.

After 12 days, i.e., after 12 × 24 hours clock B will lose 16 minutes and will show 11:44 am.

The two clocks will show the same time after 135 days The time difference has to be 12 hours between then = 720 minutes.

A will gain 540 minutes in 135 days. B will lose 180 minutes in 135 days Total 720 minutes.

Further if we consider only time then the problem becomes simpler Total difference of minutes between the times shown by the clocks after 36 hours = $16/3$ minutes difference in 1 day = 12 × 60 minutes difference in $3/16$ × 12 × 60 = 135 days.

Answer: (d)

Clearly, the first watch will show the correct time when it has gained 12 hours

i.e., (12 × 60) = 720 min and the second watch will show the correct time when it has lost 720 min.

Time taken by first watch to gain 720 min = 720 days.

Time taken by second watch to gain 720 min = (720 ÷ 1 $1/2$) days = (720 × $2/3$ days) = 480 days.

So the first watch shows correct time after every 720 days and the second watch after every 480 days.

Therefore, Time after which both the clocks will together tell the correct time = L.C.M. of 720 and 480 = 1440 days.

Answer: (c)

Clearly, time in London is 5 hrs 30 minutes behind 2.35 a.m. which is 9.05 p.m. or 21.05 hrs.