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

517 views

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?

posted Sep 2, 2016

Let the distance mentioned here be = D
Then D = 114 × T1 = 38 × T2
T1/T2 = 38/114 ( Note here that T2 is greater than T1 )
Now average speed is dependent on how speed the object is moving and for what length of time that speed is maintained.
Since the distance travelled in both the cases are same and there are 2 speeds here the slower speed will be coupled with longer time needed and vice versa.
So the average speed will be needing the ratio of the time of travel of each run to that of the total travel time in its calculations
.

There is also a shortcut for this. You can use the formula of harmonic mean for 2 terms ie., 2ab/(a+b) to get the same result. Here a and b are the 2 speeds. This works only if the distance travelled in both the cases are the same.

Similar Puzzles

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?

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?

A car covers its outward journey at 66 mph.

It returns, over exactly the same distance, at 33 mph.

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

A helicopter covers its outward journey at 330 mph.

It returns over exactly the same distance at 220 mph.

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

–1 vote

A coach covers its outward journey at 50 mph.

It returns, over exactly the same distance at 33.3333 mph.

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