Question

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

Answer 1

Answer:

Given that Ravi starts for his school at 8.20 am.

Let the distance be x km.

Let the time taken by Ravi to reach the school be y.

(1) Given that he travels at a speed of 10km/hr and reaches by 8 minutes late.

x/10 = y + 8/60

x/10 = y + 2/15 --- (1)

(2) Given that he travels at a speed of 16km/hr and reaches by 10 minutes early.

x/16 = y - 10/60

x/16 = y - 1/6. ----- (2).

on solving (1) and (2), we get

x/10 - x/16 = 2/15 + 1/6

3x/80 = 9/30

x = 9 * 80/3 * 30

= 8 km. ----- (3)

Substitute (3) in (2), we get

8/16 = y - 1/6

y - 1/6 = 8/16

y - 1/6 = 1/2

y = 1/6 + 1/2

= 2/3 hours

= 2/3 * 60

y = 40 minutes.

Ravi starts school at 8.20am + 40 minutes = 9.00AM.

His school starts at 9.00AM.