Sign up to receive Decoded, a new monthly digest with product updates, feature release info, continuing education opportunities, and more.

I have an algebra question I cant figure out - Any help is appreciated

1. (6pts) Susan used 3 of concrete to pour a rectangular slab for a small shed on her property. If the 4-in. thick slab is 18-ft. longer than it is wide:

a) How much area ( ) does it cover in her backyard?

b) How long (ft) is each side?

1. (6pts) Susan used 3 of concrete to pour a rectangular slab for a small shed on her property. If the 4-in. thick slab is 18-ft. longer than it is wide:

a) How much area ( ) does it cover in her backyard?

b) How long (ft) is each side?

Anyway, here's a partial answer using 18 ft.:

Volume is H * W * L, and 4 inches = 1/3 feet, so we have this so far. (We converted inches to feet so all numbers use the same measurement.)

3 something = 1/3 * W * L

But we also know that the length is 18 ft. longer than the width, so our expression now looks like this:

3 something = 1/3 * W * (W + 18)

If that "3 something" really is cubic yards, it will need to converted to cubic feet, since the other measurements are in feet. Since 1 cubic yard is a 3ft x 3ft x 3ft cube, or 27 cubic feet, our expression becomes this:

81 cubic feet = 1/3 * W * (W + 18)

Solve for W, and you have the width of the slab.

81 cubic feet = 1/3 * W * (W + 18)

you said yards cubed is different, so how should the equation look?

Think about the reasonableness of those numbers. Although it would be a little big, a 15 ft x 33 ft slab makes sense. A 225 ft x 243 ft slab is 3 or 4 times bigger than my entire house.

Based on your insistence of "how should the equation look" I must refer you to the EE Homework Policy. You are asking us to give you the answer, without doing any thinking yourself.

81 cubic feet = 1/3 * W * (W + 18)

So, you then said yards cubed is different, so how should the equation look?

In other words, "3 yards cubed" is 9 times larger than "3 cubic yards."

81 cubic feet = 1/3 ft * W * (W + 18)

When you reduce that to get "w squared = 225" you actually get "W squared = 225 ft squared."

1 - the thickness (or height) is 4 inches or 1/3 foot.

2 - the total volume is 3 cubic yards OR 1 yd. * 1 yd. * 1 yd.

3 - the total volume is 3 ft. * 3 ft. * 3 ft. = 27 cubic feet

4 - the VOLUME = length * width * height OR VOL = AREA * height

5 - AREA = VOL / height

6 - If one side is X feet, then AREA = X * (X + 18)

2 - the total volume is 3 cubic yards OR 1 yd. * 1 yd. * 1 yd.

3 - the total volume is 3 ft. * 3 ft. * 3 ft. = 27 cubic feet

4 - the VOLUME = length * width * height OR VOL = AREA * height

5 - AREA = VOL / height

6 - If one side is X feet, then AREA = X * (X + 18)

You will not get a correct answer if you divide 27 cubic feet by 4 inches!

If you divide cubic feet (

So, you can never get a length in inches to CUBIC FEET! The 4 inch thickness MUST be converted to feet!

A cubic yard is 27 cubic feet (3*3*3)

3 cubic yards is 81 cubic feet (27*3)

If the depth is 4 inches then the Area would be 81*3 or 243 Sq Feet (4" being 1/3 ft)

Then x being the Width then

X * (X+18) = 243

Since the only Integer that x could be would be 9

9 * (9 + 18) = 243

or 9*27 = 243

Of course you are correct - my calculation said:

I should have indicated:

If you also allow multiplication by an area, then a volume of 1 cubic foot can have a base of 3 square feet and a height of 4 inches.

If the depth was only 4" then the area would be 27 square feet if it was 12 " thick and 81 square feet if it was only 1/3 of that

27 / (1/3)

There was much confusion in the responses about 3 cubic years vs 3 yards cubed. There is not a single concrete supplier in North America who sell by anything but Cubic yards (except some in Canada who sell by the Cubic Meter)

There is only one answer to the question.

Accepted answer: 0 points for JohnMac328's comment #a39883359

for the following reason:

I don't see another answer

All Courses

From novice to tech pro — start learning today.