Question

Bharat and ingrid leave their building at the same time on their bikes and travel in opposite directions. If bharat's speed is 12 kilometers per hour and the Ingrid's speed is 14 kilometers per hour, how long will it take until they are 78 kilometers apart ?

Answer 1

3 hours

Explanation:

speed of Bharat = 12kilometers / hour

speed of Ingrid=14 kilometers / hour

For this problem we'll be using formula relating time, distance and speed.i.e

Distance = speed x time

Suppose Bharat is riding at a distance of 'b' kilometers, therefore time taken by him will be:

Time = distance/ speed

Time= b/12 hours.

Also, Ingrid can ride the distance at this time with speed of 14km/hr

The distance would be,

Distance = speed x time

Distance = 14 x (b/12) => 14b/12

Distance= 7b/6

Let '
`d_(b)`' be the distance that Bharat have covered after time 't'

therefore,
`d_(b)` = 12 x t

Let '
`d_(i)` ' be the distance that Ingrid have covered after time 't'

therefore,
`d_(i)` = 14 x t

In order to find the time when they are 78 kilometers apart, we will add
`d_(i)` and
`d_(b)`, because they are travelling in opposite direction creating distance between them.

So,

`d_(i)` +
`d_(b)` = 78

( 14 x t) + (12 x t) =78

14t + 12t =78

26t= 78

t= 78/26

t= 3hours.

thus, it will take 3 hours until they are 78 kilometers apart