Posted by **Katherine** on Wednesday, September 22, 2010 at 5:19pm.

In Wilbur's math class, his grade is based on the average score of six tests, each worth 100 points. Wilbur always worries about his grade. He knows that his average on the four first tests is 88.5. What is the lowest average he could get on his next two tests and still average 90 overall...

please help me i am very confused.....

i need the formula

- Math -
**Ms. Sue**, Wednesday, September 22, 2010 at 5:23pm
4 * 88.5 = 354 Total points so far

600 * 0.9 = 540 Total possible for 6 tests

540 - 354 = 186

186/2 = 91 average on the next two tests

- Math -
**Katherine**, Wednesday, September 22, 2010 at 5:30pm
can i get the formula...please

this is what i got.....

the formula is (88.5 + x + y) divide 3=90

90 * 3 =270

so then (88.5 + 91.5 + 90)=270 /3=90

90*3=270

- Math -
**Ms. Sue**, Wednesday, September 22, 2010 at 5:32pm
I don't understand your formula. But you didn't get an answer for your problem.

- Math -
**Katherine**, Wednesday, September 22, 2010 at 5:34pm
But the total average has to be 90 not 91 . So we are right , right ?

- Math -
**Ms. Sue**, Wednesday, September 22, 2010 at 5:36pm
The total average must be 90. But Wilbur only has 88.5 average at this point. His average grade on the next two tests must be more than 90 for his overall average to be 90.

- Math -
**Katherine**, Wednesday, September 22, 2010 at 5:50pm
no it doesnt . Because if you add 88.5+90+91.5 you get 270 and then you divide 3 you get 90.

- Math -
**Ms. Sue**, Wednesday, September 22, 2010 at 5:56pm
I'm sorry you didn't understand my explanation. I averaged grades for 32 years in my teaching career and should know what I'm talking about. You cannot bring up an 88.5 average to 90 with only a couple of 90 test scores.

Please sit down with your teacher to have him/her explain this problem to you.

- Math -
**Katherine**, Wednesday, September 22, 2010 at 5:59pm
Ok i dont understand your formula either. Im sorry, but thankyou anyways. OKAY !!!!

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**Mr. R**, Monday, December 19, 2011 at 12:58pm
Use The following equation:n 2x+4(88.5)/(6)=90. Solve for x.

x=93

- Math -
**clare**, Saturday, November 17, 2012 at 11:53am
IDK

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**Shaniqua**, Tuesday, January 22, 2013 at 6:57pm
Why multiple by 0.9???

- Math -
**Mr. H**, Tuesday, April 16, 2013 at 7:01pm
I got 94

Im a bad teacher

- Math -
**Cindy**, Tuesday, July 15, 2014 at 11:06am
You multiply by .9 since that in percentage is 90%. He wants a total average of 90% for his remaining tests. The answer is 91.

- Math -
**Kid**, Tuesday, March 3, 2015 at 4:25pm
I got 93

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