Question

A person jogs 4.0 km in 32 minutes , then 2.0km in 22 minutes and finally 1.0km in 16 minutes . What is the joggers average speed in km per minute?

Answer 1

`0.1 \ km/min`

Step-by-step explanation:

We know speed , s is given by
`s=(distance)/(time).`

NOW,

Average speed , S is given by:

`S=(total \ distance\ covered)/(total\ time \ taken )`. .....eqn 1.

Total distance covered ,
`D=4+2+1 \ km=7 \ km`.

Total time taken,
`T=32+22+16\ min=70 \ min.`

Putting these values in equation 1.

We get,

`S=(7)/(70) \ km/min=0.1\ km/min.`

Answer 2

Average speed is defined as ratio of total distance covered and total time

now we will have

`d_1 = 4 km`

`t_1 = 32 min`

`d_2 = 2 km`

`t_2 = 22 min`

`d_3 = 1 km`

`t_3 = 16 min`

now total distance moved is

`d = d_1 + d_2 + d_3`

`d = 4 + 2 + 1 = 7 km`

total time is given as

`t = 32 min + 22 min + 16 min`

`t = 70 min`

now average speed is given as

`v_(avg) = (d)/(t)`

`v_(avg) = (7)/(70) = 0.1 km/min`

so its average speed is 0.1 km per minute