Posted by Katherine on .
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,
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,
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,
I don't understand your formula. But you didn't get an answer for your problem.

Math 
Katherine,
But the total average has to be 90 not 91 . So we are right , right ?

Math 
Ms. Sue,
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,
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,
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,
Ok i don't understand your formula either. Im sorry, but thankyou anyways. OKAY !!!!

Math 
Mr. R,
Use The following equation:n 2x+4(88.5)/(6)=90. Solve for x.
x=93 
Math 
clare,
IDK

Math 
Shaniqua,
Why multiple by 0.9???

Math 
Mr. H,
I got 94
Im a bad teacher 
Math 
Cindy,
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,
I got 93