Question

A varies directly and A=8 when m=20 find A when m=15 and m when A=7​

Answer 1

`A = 16` -- (a)

`m = 17.5` -- (b)

Explanation:

Given

Variation: Direct

A = 8; m = 20

First, represent the variation.

`A\ \alpha\ \ m`

Represent as an equation

`A = km`

Make k, make the subject

`k = (A)/(m)`

A = 8; m = 20; So

`k = 8/20`

`k = 0.40`

When m = 20, we have:

`A = km`

`A = 0.40 * 40`

`A = 16`

When A = 7, we have:

`A = km`

`7 = 0.40 * m`

`m = (7)/(0.40)`

`m = 17.5`