math
posted by chris
mikes average on the first four exams in econ 1A is 88. what must he earn on the next exam to raise his overall average to 90

MattsRiceBowl
I would start by figuring out how many points he has total so far.
88 average * 4 tests = 352 points.
So then the question is, 352 + how many points ALL divided by 5 tests = 90?
(352+x)/5 = 90
352+x = 450
x = 98.
Now, let's check our work.
352 + 98 = 450
450 / 5 = 90
OR...
We could use basic logic. We could say "Mike needs 2 more points in each test so far to get him to a 90 in each test. There were four tests. 4 test * 2 points a test is 8 points. So on this exam, he needs 90 points, plus 8 points to make up for the others. So he needs a 98."
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