Dhiraj goes to his school from his house at a speed of 3.8 km/hr and returns at 2.6 km/hr. If he takes 5 hours going and coming, the distance between his house and school is:
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 7.72 km.
Let the distance between the house and the school = d km
d/3.8 + d/2.6 = 5
⇒ d(1/3.8 + 1/2.6) = 5
⇒ 5d(1/19 + 1/13) = 5
⇒ 32d/247 = 1
⇒ d = 247/32 ≈ 7.72 km