Question

Christina decided to make a pen for her dog that is 6 feet wide and 11 feet long. However, after looking at the place where she wanted to put the pen, she decided the width should instead measure only 3 feet. If she wants the perimeter of the pen to stay the same, what will be the new length of the pen?

Answer 1

14 ft

Explanation:

The perimeter of the pen Christina first decide to make is;

Perimeter = L + L+ W + W

= 6 ft + 6 ft + 11 ft + 11 ft

=34 feet

Now she wants the width to be only 3 ft and the perimeter to be the same.

34 ft = L + L + 3 ft + 3 ft

34 ft = 2L + 6 ft

subtract 6 ft from both sides of the equation to give you;

28 ft = 2L

Divide both sides of the equation by 2 to give you;

L = 14 ft