Question 1137453
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Algebraically....<br>
{{{4(88)+x = 5(90)}}}<br>
Or here is a way you can work problems like this involving averages of numbers that are all close together.<br>
Her current average after 4 tests is 88; she wants an average of 90 after 5 tests.<br>
On average, her 4 tests are each 2 points below the average she wants after 5 tests.  That means her current point total is 8 points below what she needs to get the average she wants.  And that means the 5th test has to be 8 points above the average she wants.<br>
So the score she needs to get the 90 average for the 5 tests is 90+8 = 98.