Question

The area (A) of a rectangle varies jointly as the length (l) and the width (w), and whose A = 60 sq. cm when l = 4 cm and w = 3 cm. What is the area of rectangle if the length is 6 cm and whose width is 3 cm? ​

Answer 1

The area is 90 sq. cm

Explanation:

Given

The variation can be represented as:

`A\ \alpha\ l * w`

Area = 60, when l = 4 and w = 3

Required

Find Area, when l = 6 and w = 3

Represent the variation as an equation

`A = k(l * w)`

Where k is the constant of variation.

Substitute 60 for A, 4 for l and 3 for w

`60 = k * (4 * 3)`

`60 = k * 12`

Make k the subject

`(60)/(12) = k`

`5=k`

`k=5`

To get the value of Area when l = 6 and w = 3.

Substitute 5 for k, 6 for l and 3 for w in
`A = k(l * w)`

`A = 5 * 6 * 3`

`A = 90`

The area is 90 sq. cm