SOLUTION: A person's average was 64%. One the next test he got 68%. This raised his average to 65%. The next test, his average improved by 1% again. What did he get on the last test?
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-> SOLUTION: A person's average was 64%. One the next test he got 68%. This raised his average to 65%. The next test, his average improved by 1% again. What did he get on the last test?
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Question 808437: A person's average was 64%. One the next test he got 68%. This raised his average to 65%. The next test, his average improved by 1% again. What did he get on the last test?
I thought of doing trial and error: I tried adding everything and dividing by the amount plus the number of extra 64s, but it took too long. I still don't know what the answer is. Please help me! Answer by KMST(5328) (Show Source):
You can put this solution on YOUR website! We assume the 64% average was the average of tests.
THe sum of the grades of those tests was .
When the next test grade was 68%, the sum of the grades of all the tests was , and since there were tests by then,
the average was .
We are told that average was 65%, so --> --> --> --> .
So the average was 64% after 3 tests and 65% after 4 tests.
After the 5th test, the average was 1% higher (than 65%),
so it was 65% + 1% = 66%.
The sum of the first 4 tests was
With a percentage score of on the fifth test,
the sum of the grades on the first 5 tests is
The average for the first 5 tests can be calculated as
and since the average is 66%, --> --> --> -->