1985 AJHSME Problems/Problem 17
Problem
If your average score on your first six mathematics tests was and your average score on your first seven mathematics tests was , then your score on the seventh test was
Solution
Solution 1
If the average score of the first six is , then the sum of those six scores is .
The average score of the first seven is , so the sum of the seven is
Taking the difference leaves us with just the seventh score, which is , so the answer is
Solution 2
Let's remove the condition that the average of the first seven tests is , and say the 7th test score was a . Then, the average of the first seven tests would be
If we increase the seventh test score by , the average will increase by . We need the average to increase by , so the seventh test score is more than , which is clearly . This is choice
See Also
1985 AJHSME (Problems • Answer Key • Resources) | ||
Preceded by Problem 16 |
Followed by Problem 18 | |
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