Question

It takes billy 6 minutes to walk 1.5 km. How long will it take billy to walk 9km?

Answer 1

It will take Billy 36 minutes to walk 9km.

Answer 2

`\boxed{\tt 36 \ minutes}`

Explanation:

Let's make a proportion using the following setup:

`(minutes)/(kilometers) =(minutes)/(kilometers) \\`

We know it takes Billy 6 minutes to walk 1.5 kilometers.

`(6\ minutes)/(1.5\ kilometers) =(minutes)/(kilometers)`

We don't know how long it takes him to walk 9 kilometers, so we can say it takes him x minutes to walk 9 kilometers.

`(6\ minutes)/(1.5\ kilometers) =(x\ minutes)/(9\ kilometers)`

`(6)/(1.5) =(x)/(9)`

Now, solve for x. To do this, isolate x on one side of the proportion. x is being divided by 9. The inverse of division is multiplication. Multiply both sides of the proportion by 9.

`9*(6)/(1.5) =(x)/(9)*9`

`9*(6)/(1.5) =x`

`9*4=x`

`36=x`

x= 36 minutes

It will take Billy 36 minutes to walk 9 kilometers.