Question

if y varies directly as x, and y is 6 when x is 72, what is the value of y when x is 8? a. 1/9 b. 2/3 c. 54 d. 96

Answer 1

The value of y when x is 8 is b. 2/3

Answer 2

The correct option is b.

Explanation:

It is given that y varies directly as x.

`y\propto x`

`y=kx`

It is given that y is 6 when x is 72.

`6=k* 72`

Divide both sides by 72.

`(1)/(12)=k`

The constant of proportionality is
`(1)/(12)`.

`k=(y)/(x)`

`(1)/(12)=(y)/(8)`

`(1)/(12)* 8=y`

`(2)/(3)=y`

The value of y is
`(2)/(3)`. The correct option is b.