LR - Clocks - Previous Year CAT/MBA Questions

Answer: Option D

Explanation :

The pace of Jim's watch is slower by 3 minutes in comparison with Kim's watch for every one hour. The difference increases as the hours pass by.

The time and "am" and "pm" of the watch coincide when the difference between the two clocks reduces to 24 hours. The two clocks display the same time including am and pm.

For a difference of 24 hours, the clock needs to lag by 1440 minutes.

For every one hour, the clock lags by 3 minutes. Hence in order to have a difference of 1440 minutes, it takes $\frac{1440}{3}$ = 480 hours. This is equivalent to 20 days of time.

Hence for every twenty days, they display the same time.

In the period of Jan 1 and June 1, there are 150 days which includes 7, 20-day intervals. Along with the 7 times once on Jan 1st and once on June 1st, they display the same time.

Answer: Option B

Explanation :

At exactly 10 AM, angle between the two hands = 60 degrees
Applying the concept of relative velocity, we can say that the minute hand has to travel 180 - 60 = 120 degrees more at a relative velocity of 5.5 degrees/minute
Hence, time taken to make 180 degree angle between the 2 hands = 120/5.5 = 22 minutes

Answer: Option B

Explanation :

Angle between 2 & 4 at the centre is 60⁰. In 20 minutes, the hour hand moves 10⁰. Thus, angle between the two hands at 2 hrs. 20 minutes would be
60 – 10 = 50⁰.

Hence, option (b).

Answer: Option C

Explanation :

At 3:10, the hour hand is pointing south. So according to this position, the 9 hour mark is in the North and the 12 hour mark is in the east. The minute hand will point east when it points to the 12 hour mark, which will be after 50 minutes.

Hence, option (c).