please help me with my work and please tell me how you got the answer?

Question

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 grades. He knows that his average on the first four test is 88.5.What is the lowest average he could get on his next two test and still average 90 overall?

**Please dont answer if your not going to do it rite or dont know the answer,thank u

Answer 1

He needs a total of 540 points to make a 90 average on 6 tests.
After 4, he has an average of 88.5, so he has 354.points.
He needs another 186 points to get to 540.
186 / 2 = 93.

Answer 2

What you have here is a situation in which you have the final % desired (90%), and an initial % to work with. You know it has to be over 90% to bring that 88.5 % up to 90%. So, heres how you do it:
it always helps to write down the information you are given, and then what you're missing.
tests taken: 4
tests to take: 2
percentage of tests left to take: 2/6 or 33.3%
average so far: 88.5 %
score desired: 90 %
now you need a formula that will give you your answer. If you were to average A % and another percentage, lets call it X%, you want to end up with 90 %. You know that A % is 4/6 of the total, and X % is 2/6 the total. You also know that A is 85.5. So, set up your formula:
(4/6) x 88.5 % + (2/6) x X % = 90%
lets simplify this a little with the calculator
59 + X/3 = 90
solve for X by subtacting 59 from both sides and then multiplying by 3
X = 93
so there is your answer. Wilbur has to get at least 93% on his next two exams.

Answer 3

Ok, I think this is it. The number you would get if you had 6 tests and an average of 90 before you divide by 6 is 540.

a + b + c + d + e + f = 540 / 6 tests = average of 90

So take 4 tests averaging 88.5 and work backwards.
88.5 X 4=354

The difference between 4 test averaging a 88.5 and 6 tests averaging a 90 is 540-354 which = 186. Divide that number by the 2 remaining test, and the answer is he cannot raise his grade to a 90 without getting a 93 on each of the tests.

Answer 4

93