Ravi starts for his school at 8:20 a.m. on his bicycle. If he travels at a speed of 10 km/h. then he reaches his school late by 8 minutes but on travelling at 16 km/h he reaches the school 10 minutes early. At what time does the school start?

Let the total distance = x km

Let the time taken by Ravi to reach the school at sharp time = t min

If the speed of the bicycle is 10km/h, then he reaches his school late by 8 min

∴  

⇒      (1)

If the speed of the bicycle is 16km/h, then he reaches his school 10min early.

∴

⇒      (2)

On subtracting equation (2) from (1)

⇒

⇒

⇒

⇒

Now, put x = 8 in Eq. (i),
we get

⇒

Hence starting time of school is 8:20 + 40min i.e. 9:00am