Problem
Each member of a research group visited either the Virgin Islands or Hawaii...
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So What?
Math questions involving two equations and two unknowns can usually be combined into one equation with one unknown.
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SAT: Grid-In Question #7 |
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Question:
When a test is administered to 8 students, the average (arithmetic mean) of the scores is 85. If 2 more students take the test and receive scores of 90 and 100, what is the average score of all the test takers?
| Remember that the average |
= |
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. |
| In the original group of test takers, the average score is 85 and |
| the number of test takers is 8, so you can plug in these numbers |
| to solve for the sum of the scores. |
| You have |
85 |
= |
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, and the sum of the scores |
= |
| When 2 more students take the test, they receive scores of |
| 90 and 100. So the new sum of the scores is: |
| 680 |
+ |
90 |
+ |
100 |
= |
870 |
, and the new number of test takers is: |
| Substituting these values into the average formula, you have that: |
| the average |
= |
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870 |
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 |
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10 |
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= |
87 |
. Hence, the average score of all the |
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