Mohan walking at a speed of 20 km/h reaches his office 1 h late. Next time he increases his speed by 5 km/h, then he reaches his office 30 min early. What is the distance of his office from his house?
Correct Answer: 150 km
Explanation:
Distance of his office from his house = {ab/(b - a)} x (t1 + t2)
Here, a = 20 km/h, t1 = 1 h, b = 20 + 5 = 25 km/h
and t2 = 30 min = 0.5 h
∴ Distance = {20 x 25/(25 - 20)} x (1 + 0.5) = 500(1.5)/5
= 100 x 1.5 = 150 km
