If a boy goes from his home to his school at a speed of 40 km/h, he reaches 10 minutes early. If he goes at a speed of 35 km/h, he reaches 5 minutes late. What will be the time taken for the journey at a speed of 35 km/h?

120 minutes

The ratio of the speed of boy,

 S1 ∶ S2 = 40 ∶ 35

 S1 ∶ S2 = 8 ∶ 7

As speed is inversely proportional to Time .

So , The ratio of time,

 T1 ∶ T2 = 7 ∶ 8

According to the question,

1R = 15 minutes

8  units = 15 × 8 = 120 minutes

So , the boys takes 120 minutes for the journey with 35 km/h.