rrobiinn wrote:If a boy takes as much time in running 10m as a car takes in covering 25m, the distance covered by the boy during the time the car covers 1km, is what?

Whenever you can rephrase a question to read, "For every X something else happens", we can typically solve the question using equivalent ratios.

Here, we have "For every 10m a boy travels, a car travel 25m"
Here, we're comparing the boy's distance to the car's distance.
We want to know the number of meters the boy travels during the time the car travels 1km (1000m).

Let B = the number of meters the boy travels during the time the car travels 1000m

Equivalent ratios
boy's distance/car's distance: __ 10/25 = B/1000

To solve, cross multiply to get: 25B = (10)(1000)
Solve for B to get B=400m

Cheers,
Brent