Question

A boy runs at a speed of 20 m/s.How much time will he take to cover a distance of 1 km?

Answer 1

I got `50s`

Explanation:

1 km corresponds to `1000m` so considering that:
`"speed"="distance"/"time"`
we can rearrange and get:
`"time"="distance"/"speed"=1000/20=50s`

Answer 2

It will take 50 seconds to run 1000 metres

Explanation:

Using ratio in the fraction style format

Given:`" "("distance")/("time")-> ("metres")/("seconds")->20/1`

We need 1 km which is the same as 1000m

Let the unknown time in seconds be `t`

`20/1-=1000/t`
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To change 20 into 1000 multiply by 50

If you multiply by 1 you do not change the value. However, 1 can come in many forms.

`color(green)(20/1color(magenta)(xx1)" "-=" "20/1color(magenta)(xx50/50))color(blue)(" " =" " 1000/50)`

It will take 50 seconds to run 1000 metres