WEBVTT

1
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Here is the problem: The average of 4, 8 and x is 7. Find x.

2
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The mean of 4, 8 and x is 7.

3
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Total needed. 3 values with mean 7 sum to 3 times 7 equals 21.

4
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Solve for x. x equals 21 minus (4 plus 8) equals 21 minus 12 equals 9.

5
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So the answer is x equals 9.

6
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The mean of 4, 8 and x is 7.

7
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(4 plus 8 plus 9) / 3 equals 7, which checks out.