Ines G.

asked • 03/07/16

if the bulletin board measures 52 inches by 74 inches and we wants to have a usable area of 3,128 square inches,what is the widest possible border?

I need help finding the widest possible border

1 Expert Answer

By:

Mark M. answered • 03/07/16

Tutor
5.0 (278)

Mathematics Teacher - NCLB Highly Qualified

See tutors like this
See tutors like this
This is a "doughnut hole" problem. You want to determine the size of the doughnut when the hole (the usable space) is removed.
 
Draw  a diagram and label.
The board is 52 by 74.
The usable space is 52-2x by 74-2x
(52 - 2x)(74 - 2x) = 3128.
 
Can you solve for x? That is the width of the border.
Upvote • 0 Downvote
More
Report

Andrew M.

Multiplying out Mark M's equation you get a quadratic of:
4x2 -252x + 720 = 0
Every term is divisible by 4 so reduce this to:
x2 - 63x + 180 = 0
 
From there Use the quadratic equation to solve for x;
x = [-b ±√(b2-4ac)]/2a   with a=1, b=-63, c=180
 
(You should find x=3 inches as the width of the border)
Report

03/08/16

Still looking for help? Get the right answer, fast.

Ask a question for free

Get a free answer to a quick problem.
Most questions answered within 4 hours.

OR

Find an Online Tutor Now

Choose an expert and meet online. No packages or subscriptions, pay only for the time you need.