Question

A direct variation exist between x and y. When x=4, y=3. What is the value of y when x=10

Answer 1

`y = 7.5`

Explanation:

Given

Direct variation implies that:

`y = kx`

Where k is the constant of variation.

`x=4; y=3`

Required

Find y when
`x = 10`

`y = kx`

Make k the subject

`k = (y)/(x)`

For:
`x=4; y=3`

`k = (3)/(4)`

For:
`x = 10`

`k = (y)/(x)` becomes

`k = (y)/(10)`

Substitute
`k = (3)/(4)`

`(3)/(4) = (y)/(10)`

Make y the subject

`y = (3)/(4) * 10`

`y = (3* 10)/(4)`

`y = (30)/(4)`

`y = 7.5`