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Smart Math Time Speed Distance

[Smart Math] Time Speed Distance Problem 1

Here’s and example of a SMART MATH problem for TIME SPEED DISTANCE.

Time Speed Distance

Problem

My watch is 1 minute slow at 1.00 pm on Tuesday and 2 minutes fast at 1.00 pm on Thursday. When did it show the correct time?

  1. 1.00 am on Wednesday
  2. 5.00 am on Wednesday
  3. 1.00 pm on Thursday
  4. 5.00 pm on Wednesday
  5. 5.00 pm on Thursday

The Usual Method

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Between 1.00 pm on Tuesday and 1.00 pm on Thursday, there are 48 hours. Thus in 48 hours, the watch gains 1 + 2 = 3 minutes.

Hence, it gains 1 minute every \frac{48}{3}=16 hours.

Thus to show the correct time, it will have to gain 1 minute. Hence, we need to add 16 hours to 1.00 pm on Tuesday. 16 hours can be broken in to 12 + 4 hours.

12 Hours + 1.00 pm on Tuesday = 1.00 am on Wednesday.

4 Hours + 1.00 am on Wednesday = 5.00 am on Wednesday.

(Ans: 2)

Estimated Time to arrive at the answer = 45 seconds.

Using Technique

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Assume that the clock is 1 minute slow on Tuesday at 1.00 pm and 1 minute ahead on Thursday at 1.00 pm. Hence, the clock will show the correct time at 1.00 pm on Wednesday.

But the real gain of time is faster than assumed above. Thus the clock will show the correct time earlier than1.00 pm on Wednesday. The closest option is option ‘2’.

(Ans: 2)

Estimated Time to arrive at the answer = 10 seconds.
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