Question

A rectangle with dimensions of 3 units by 7 units is enlarged by a scale factor of 1.1. By what percent does it’s area increase?

Answer 1

`21\%`

Explanation:

Original dimensions of the rectangle

`l=7\ \text{units}`

`w=3\ \text{units}`

Area of the rectangle

`A=7* 3=21\ \text{units}^2`

Scale factor = 1.1

New dimensions

`l'=7* 1.1=7.7\ \text{units}`

`w'=3* 1.1=3.3\ \text{units}`

The new area of the rectangle

`A'=7.7* 3.3=25.41\ \text{units}^2`

Percentage change is given by

`(A'-A)/(A)* 100\\ =(25.41-21)/(21)* 100=21\%`

The percentage by which the area of the rectangle increases is
`21\%`.