Question

If y is 4.5 when x is 3, and y varies directly with x, find y when x is 9. 1.5 7.5 10.5 13.5

Answer 1

13.5

Step-by-step explanation

It was given that, y varies directly as x.

Therefore, the variation equation is of the form:

`y = kx`

If y is 4.5 when x is 3, then we can substitute to find the constant of variation.

`4.5 = 3k`

Divide both sides by 3;

`k = (4.5)/(3)`

`k = (3)/(2)`

Hence the equation becomes:

`y = (3)/(2) x`

When x=9,

`y = (3)/(2) * 9 = 13.5`