# What was their average speed over the entire journey?

544 views

Early one morning a family travelled to a shopping centre at 35 km/h.

After a day of Christmas shopping they returned, over exactly the same distance, at a crawl of only 14 km/h.

What was their average speed over the entire journey?

posted Dec 12, 2017

Average Speed = Total distance/ ( Total time)
= 2D/(D/35 + D/14)
= 2/((14 + 35)/(35×14))
= 2×35×14/49
= 20 KMPH. { Neglecting time spent on shopping }.

–1 vote

v=(35+14)/2=49/2=24.5 km/h

Similar Puzzles

A cyclist covers his outward journey at 15 mph.

The return, over exactly the same distance, is uphill. He completes it at 5 mph.

What is the cyclist's average speed over the entire journey?

A caterpillar covers its outward journey to a vegetable patch at a speed of 114 metres per hour.

After filling up with his favourite foods the caterpillar returns, over exactly the same distance, at 38 metres per hour.

What is the caterpillar’s average speed over the entire journey?

An aeroplane covers its outward journey at 600 kmph.

It returns, over exactly the same distance, at 400 kmph.

What is the average speed of the aeroplane over the entire journey?