Indian Institute of Foreign Trade 2015 Solved Paper

(b) Let Morning speed = 10 kmph
∴ Evening speed = 15 kmph
and morning time = 1 hour
Evening time = 1.5 hour
∴Distance in the morning = 10 × 1 = 10 km
Distance in the evening = 15 × 1.5 = 22.5 km
Average speed =

Total‌distance

Total‌time

For entire journey =

10+22.51

1+1.5

=

32.5

2.5

=13 km ...(1)
Average speed in morning =

10

1

= 10 kmph .....(2)
Clearly average speed is 30% greater.