Question 664315
Average is the (sum of the numbers)/(the # of numbers)
Given 3 numbers and the average, plug them into the equation, where x is the unknown 4th score
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(91 + 89 + 84 + x)/4 = 90
Solve for x
Combine like terms
(264 + x)/4 = 90
Multiply by 4
264 + x = 360
Isolate x
x = 360 - 264
x = 96
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Zachary must score a 96
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