##### Write and solve an equation to find out the value of x.

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Randy had grades of 85, 92, 96, and 89 on his last four math tests. What grade does he need on his next test next test to have an average of 92?

Mar 27th, 2015

You could build an equation by having x stand in for the missing score. Then you have scores of 85, 92, 96, 89 and x.

You're told the average of these is 92. Now the average (mean) of a group of numbers is their sum, divided by their count (how many there are):

Average = (85 + 92 + 96 + 89 + x)/5

92 = (85 + 92 + 96 + 89 + x)/5

Multiply both sides by 5:

92*5 = (85 + 92 + 96 + 89 + x)

Simplify both sides:

460 = 362 + x

x = 460-362

x = 98

Mar 27th, 2015

thank you for your help on my math question

Mar 27th, 2015

thank you for your help on my math question

Mar 27th, 2015

No problem, aleisha :-)

Mar 27th, 2015

Mar 27th, 2015

Go ahead and post them, I'll keep an eye out.

Mar 27th, 2015

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Mar 27th, 2015
Dec 8th, 2016
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