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