Question 1185474
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To have an average of 70 on 6 tests, the total of her scores needs to be 6*70=420.<br>
Add the given five test scores and subtract that total from 420 to get the answer.<br>
Or you can do it like this, by comparing each of the five given test scores to the desired average:<br><pre>
  66  -4
  64  -6
  84 +14
  58 -12
  79  +9
--------
     -22+23 = +1</pre>
Overall, her current five test scores put her 1 point above her desired average; that means her next score must be 1 point below that average.<br>
ANSWER: She needs a score of 69 (-1) on her next test to get an average of 70.<br>