Question

If a boy walks from his house at 4 km/hr, he reaches school 10 minutes early. If he walks at 3 km/hr, he reaches 10 minutes late. What is the distance from his house to school ?
1. 6 km
2. 4 km
3. 5 km
4. 3 km

Answer 1

Correct Answer - Option 2 : 4 km

Given:

Distance = Speed × Time

Calculation:

Let the distance from house to school be d km and original speed be s km/hr

Original time taken to reach school = Distance/Speed = d/s

Now, A/Q

d/s - d/4 = 10/60      ----(1)

d/3 - d/s = 10/60      ----(2)

Adding eq (1) and eq (2)

(d/3) - (d/4) = (1/6) + (1/6)

⇒ d/12 = 1/3

⇒ d = 4 km

∴ The distance from house to school is 4 km