# Fast And Slow Clocks YouTube Lecture Handouts for Aptitude Questions for PAR

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## Fast and Slow Clocks

## Get this Terminology- Important!!!

If a clock's hands are moving, it is running. This is the mechanical sense of run, like a car or a pump or a meter.

Fast and slow refer to the displayed time:

If a clock's hands take 59 minutes to complete one hour, it is running fast. If the clock displays 5:00 and it's known to be 4:59, the clock is (or is running) fast.

If a clock's hands take 61 minutes to complete one hour, it is running slow. If the clock displays 5:00 and it's known to be 5:01, the clock is (or is running) slow.

A watch which gains time uniformly is 5 minutes slow at 8’O clock in the morning on Sunday and is 5 minutes 48 seconds fast at 8 PM the following Sunday. When was it correct?

A clock is set right at 8 AM. The clock gains 10 minutes in 24 hours. What will be the true time when the clock indicates 1 PM the following day?

How much inaccurate does a watch become per day, if its hands coincide every 64 minutes?

The inhabitants of planet Mars measure time in different hours and minutes from earth. Their day has 36 hours with each hour being 120 minutes. The dials of their clocks show 36 hours. What is the angle between the hour hand and the minutes hand of a Martian clock at 9:48? Angle around a Martian point is 720 degrees.

2 clocks A and B are now showing 3’o clock. Clock B is 2 mins/hour faster than clock

A. How long will it take them to show the same time again?

1^{st} clock gains 5 mins every 1 hour. 2^{nd} clock loses 5 mins every 1 hour. After how many hours both will show same time again?

A clock loses exactly 20 minutes every hour. It is now showing 4:00 am and was correct at midnight. The clock stopped 4 hours ago, what is the correct time now?

## Next Class: Speed Problems

Two Indian tourists cycled towards each other, one from point A and the other from point B. The first tourist left point A 6 hr later than the second left point B, and it turned out on their meeting that he had traveled 12 km less than the second tourist. After their meeting, they kept cycling with the same speed, and the first tourist arrived at B 8 hrs later and the second arrived at A 9 hrs later. Find the speed of faster tourist

And then move on to relative speed, trains, and boats ϑ…

-Mayank