Question

Jerome is painting a rectangular toolbox that is 20 inches by 10 inches by 8 inches. A tube of paint covers 300 square inches. Part B How many tubes of paint should Jerome buy?

Answer 1

2.93 but rounding because he must purchase whole tubes: 3.

Explanation:

So, to figure this out, we must recall the formula for sufrace area of a rectangle:

2*L*H+2*L*W+2*W*H

This is a bit long, so lets break it up into 3 seperate segments, and plug in values:

2*L*H

Plug in the values:

2*20*10

=

400

2*L*W

Plug in the values:

2*20*8

=

320

2*W*H

Plug in the values:

2*8*10

=

160

Now that we have solved for each segment, lets add them together to get our total surface area:

400+320+160

=

880

So this is the surface area.

Now, we know that a tube of paint covers 300 of the 880 surface area.

To find the exact amount, lets divide the 880 by the 300:

`(880)/(300)`

Simply:

`(44)/(15)`

This is sligthly less than 3, and doing it out, you actually get 2.93 with the 3 repeating.

Now we need to think about something. Lets say you are going to the grocery store, and you need 1.895893 lettuce. Do you think you will find 1.89 lettuce? No, you could get 1 or 2, but not 1.89 lettuce, that just doesnt make sense.

It is the same thing here, we have to round up. Note that when doing problems such as these, you will never round down. If you need 1.253 tubes of paint, you arent going to get 1. You are going to need 2. So note that you will always round up when you solving a problem like this.

So your answer is 3.

Hope this helps!