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Races - Quant/Math - CAT 2009
Question 4 the day:
June 30, 2003
The question for the day is from the topic of Races.
- A gives B a start of 30 seconds in a km race and still beats him by 20 m. However, when he gives B a start of 35 seconds, they finish the race in a dead heat. How long does A take to run the km?
| (1) |
250 seconds |
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(2) |
285 seconds |
| (3) |
220 seconds |
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(4) |
215 seconds |
Correct Answer - (4)
Solution:
When A gives B a start of only 30 seconds, he beats him by 20 m.
But, when he gives him a start of 35 seconds, they finish the race in a dead heat
Essentially, B is able to run 20 m in the extra 5 second start that he gets in the second instance.
Hence, B's speed = 20/5 = 4 m/sec.
As B runs at 4 m/sec speed, he will take 1000 / 4 = 250 seconds to complete a km.
A can give B a start of 35 seconds in a km race. Hence, A will take only 215 seconds to run the km.
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