Question

Suppose that y varies directly with x. Given x=4 when y=20.
Find y when x = 3

Answer 1

y = 15

Explanation:

Given: y varies directly with x, x=4 when y=20

To find: y when x = 3

Solution:

As y varies directly as x, it means that as x increases, y also increases by the same factor.

As y varies directly with x,

`y=kx`

Here, k is a constant

As x = 4 when y = 20,

`20=4k\\k=(20)/(4)=5\\\Rightarrow y=5x`

Put x = 3

`y= 5(3) = 15`