Question 1202053
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Charlie has scored 89, 78, and 63 on his previous three tests. 
What score does he need on his next test so that his average (mean) is 75?
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<pre>
Let x be the unknown score on his fourth exam.


Charlie wants  

    {{{(89 + 78 + 63 + x)/4}}} = 75,

or

    89 + 78 + 63 + x = 4*75

    230 + x = 300

          x = 300 - 230

          x = 70.


<U>ANSWER</U>.  Charlie needs to get 70 on the 4th exam.
</pre>

Solved.


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It is a typical problem on average.


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