Question

You can ride a bicycle 15 mph. Your sister rides 12 mph. You give her a one hour head start. In how many hours will you catch up if neither of you stops?

Answer 1

4 hours

Explanation:

It is given you can ride a bicycle 15 mph. Your sister rides 12 mph. You give her a one hour head start.

Your info:

Speed = 15 mph , let the distance covered be = 'x' miles , time taken to cover the distance,

time =
`(d)/(s)` =
`(x)/(15)`

Sister's info:

Speed = 12 mph , let the distance covered be = x miles, time taken to cover the distance of 'x' miles,

time =
`(d)/(s) = (x)/(12)`

Equation:

Sister's time - your time = 1

`(x)/(12)- (x)/(15) = 1`

Multiplying both the sides by 60 we get,

`5x -4 x = 60`

`x=60` miles

Therefore, your time to catch up:

`(x)/(15)=(60)/(15)=4` hours

Therefore, it will take 4 hours to catch up if neither of your stop.