- 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 (2) 285 seconds (3) 220 seconds (4) 215 seconds
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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