Question

In a kilometre race, A can give B a start of 100 m or 15 seconds. How long does A take to complete the race?

• A. 150 seconds
• B. 165 seconds
• C. 135 seconds
• D. 66.67 seconds

Answer 1

The correct option is- D 135 seconds

In a 1000 meter race, A gives B a start of 100 m or 15 seconds.
This means that B takes 15 seconds to run 100 m.
Therefore, B will take 150 seconds to run the part of 1000 meters.
1000 m = $10\times 100m$ and therefore the time taken will also be $10\times 15=150$ seconds.
B a start of 15 seconds, A takes 15 seconds less than B to complete the race.
Now we can say A will take 135 seconds to run the 1000 m or 1 km.