SOLUTION: I am trying to get an equation for averaging. There are 4 tests in algebra. Jesse scored 97,82, and 86 on the first 3 test.What does Jesse need to earn on the last test to make

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Question 151540: I am trying to get an equation for averaging.
There are 4 tests in algebra. Jesse scored 97,82, and 86 on the first 3 test.What does
Jesse need to earn on the last test to make at least a 90 average.? I think the answer has to be > 90 or 92. How do I put that in an equation? Please help
Found 2 solutions by oscargut, jim_thompson5910:
Answer by oscargut(2103) About Me  (Show Source):
You can put this solution on YOUR website!
(97+82+86+x)/4 = 90
then
265+x=90*4=360
then
x=95
Answer:Jesse needs to earn 95 on the last test

Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Let x=score on 4th test


Remember, to find the average of 4 numbers, simply add the 4 numbers up and divide that sum by 4 (the number of numbers)


So the average of the 4 tests is:

A=%2897%2B82%2B86%2Bx%29%2F4


In order to "make at least a 90 average", we need an average that is greater than or equal to 90. So this means that

A%3E=90


%2897%2B82%2B86%2Bx%29%2F4%3E=90 Plug in A=%2897%2B82%2B86%2Bx%29%2F4. In other words, replace "A" with %2897%2B82%2B86%2Bx%29%2F4


97%2B82%2B86%2Bx%3E=360 Multiply both sides by 4.


265%2Bx%3E=360 Combine like terms.


x%3E=360-265 Subtract 265 from both sides.


x%3E=95 Combine like terms on the right side.


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Answer:

So the answer is x%3E=95 which means that Jesse needs a 95 or higher on the 4th test to average a 90 or better.