Problem Solving

Hi Vincen,

We're asked to use a 20 inch string to form the perimeter of a rectangle. We're asked for the LARGEST possible rectangular area that could be created. This question is built around a relatively rare concept (while you might see it on Test Day, it would likely be just once). In simple terms, when dealing with a 'fixed' total length as described in the prompt, the largest area will be created when you form a SQUARE.

For example, with a 20 inch string, you could form the following rectangles:
A 1x9 rectangle with an area of 9
A 2x8 rectangle with an area of 16
A 3x7 rectangle with an area of 22
A 4x6 rectangle with an area of 24
A 5x5 rectangle with an area of 25

There's no other possible rectangle that will lead to an area that is larger than 25.

Final Answer: D

GMAT assassins aren't born, they're made,
Rich

Vincen wrote: ↑

Fri Sep 15, 2017 7:26 pm

Freddy has a piece of string that is 20 inches long. He wants to use the string as the perimeter of a rectangle. What is the greatest area that rectangle could have?

A) 5
B) 10
C) 20
D) 25
E) 40

The Official Answer is D.

I couldn't do the calculus to solve it. Please, help me.

The greatest possible area of a rectangle occurs if all sides are equal, so if each side is 5, the greatest area is 5 x 5 = 25.

Answer: D