<PRE><B>Question 270194</B>
Your scores are 87, 92, 84.


To get an average of 90 on all four tests, your formula needs to be:


87 + 92 + 84 + x = 90*4


Combine like terms and simplify to get:


263 + x = 360


Subtract 263 from both sides of the equation to get:


x = 360 - 263 = 97.


You need to get a 97 on the last test.


Then you would get the following:



87 + 92 + 84 + 97 = 360


360/4 = 90% overall average on the 4 tests.


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