Ravi starts for his school from his house on his cycle at 8:20 a.m. If he runs his cycle at a speed of 10 km/h, he reaches his school 8 minutes late, and if he drives the cycle at a speed of 16 km/h, he reaches his school 10 minutes early. The school starts at:

9:00 a.m.

We know that ,

Speed = \(\frac{Distance}{Time}\)

Speed ∝ \(\frac{1}{Time}\)

Ratio of speed ,    S1     :         S2

                          10      :         16

Time                   16      :         10

                           8       :          5

According to question,

( 8 - 5)R = 18 minutes

3R = 18 minutes

1R = 6 minutes

Time taken  by speed 10 km/h = 8 x 6 = 48 minutes

If he runs his cycle at a speed of 10 km/h, he reaches his school 8 minutes late

So, Actual time = 48 - 8 = 40 minutes

So, College starts at = 8:20 am + 40 minutes

= 9 am