Retired Moderator
Joined: 07 Jun 2014
Posts: 4812
Given Kudos: 0
WE:Business Development (Energy and Utilities)
Re: The length and width of a painted rectangle were each increa
[#permalink]
14 Jul 2018, 04:39
Explanation
Choose smart numbers for the dimensions of the rectangle—for instance, length = 20 and width = 10.
The original area of the rectangle = length × width = 200. After a 10% increase for both the length and the width, the area becomes 22 × 11 = 242.
Use the formula for percent change:
Percent Change =\(\frac{Difference}{Original} \times 100\%\)=\(\frac{242-200}{200} \times 100\%=21\%\)
Quantity A is greater.
Alternatively, use logic. The formula for area requires multiplying the length and the width. If just one side is increased by 10%, then the overall area will increase by 10%. If two sides are increased by 10%, then the overall area will increase by more than 10%.