What was their average speed over the entire journey?

Question

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?

Answer 1

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 }.

Answer 2

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