GED Math: Another Percent Word Problem

Yo! Here’s a sample word problem from a GED student, wants to know more about percentages:

would like to know more about percentages. like dividing. here’s a question:

jacks auto service-summary of april sales activity

division …… april sales …… increase over march
parts ………. $11,000 ……… %10
services ….. $70,000 ……… %25

what was the combined sales revenue in march for the parts and services divisions of jacks auto service? answer is $66,000 how did they get that answer step by step?

Hey! Thanks for sendin’ in a math question. This is a good one. Percents is pretty tough for a lot of people. This one is a little harder than the one last week, cuz it’s got more steps. So let me walk through it….

The first thing I do is look through the problem to get all the information it gives. This one’s got the information in a chart, so that’s pretty easy, it’s all right there.

For parts, April sales = $11,000
April parts sales is 10% more than March sales.

For service, April sales = $70,000
April service sales is 25% more than March sales.

So, the second thing I look at is, what’s it askin’? What do they want to know? And that’s the combined sales (parts + service) for March. Course, the question don’t give you the March numbers, that’d be too easy. Question is, how do you find the march numbers?

Well, let’s take parts first. I’m gonna call March parts sales P, just to have something to stand for it. April parts sales ($11,000) is (equals) 10% (10% times P, cuz they mean 10% of March parts sales) more than (plus) March part sales (P). So,

$11,000 = (10% x P) + P

Now, you gotta find P. With percent problems, first thing I always do is change the percent to a decimal, that’s just moving the decimal point 2 places to the left. So, 10% = .1 (if there’s no decimal already, it’s at the end of the number). So,

$11,000 = .1P + P

Now, a P by itself is 1P, so .1P plus P = 1.1P

$11,000 = 1.1P

So, I divide $11,000 by 1.1 to get P by itself.

$11,000/1.1 = P

That’s the same as dividing $110,000 by 11 (You can move the decimal point over one in the 1.1, as long as you move it over one space in the 11,000, too.):

$110,000/11 = P

And that’s $10,000 (11 into 11 once, then all that’s left is zeros…)

$10,000 = P

So, does it make sense? If you think about it, 10% of $10,000 is $1,000, and so $11,000 is 10% higher than $10,000. Makes sense to me!

Now, do the exact same thing for service sales, S, with the numbers for service. See how the equation is the same?

$70,000 = (25% x S) + S
$70,000 = .25S + S
$70,000 = 1.25S
$70,000/1.25 = S
$7,000,000/125 = S
$56,000 = S

So, now you know that for March, Parts sales were $10,000, and Service sales were $56,000. Add ‘em up, an’ you get $66,000 total sales….there ya’ go! So:

1) Get your info together.
2) Figure out what the questions askin’.
3) Make an equation to figure out the answer.
4) Solve step-by-step.

Special advice for percents:
For percents, change ‘em to decimals by moving the decimal two places to the left. Do this right away!

Also, when they say “something-percent more than another number”, that means “something-percent TIMES the original number PLUS the original number”

“something-percent less than another number” means “the original number minus something-percent TIMES the original number”… So, if $9,000 is 10% less than X, $9,000 = x – (.1x), so $9,000 = 1x – .1x = .9x …. x = $9,000/.9 = $10,000

Hope this helps!
Curtis

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