Statisticsmedium · Past Paper

If the arithmetic mean of 5, 7, 9, x is 9, what is the value of x?

A11
B15
C13
D17

✓ Correct Answer: B15

Sum = 5+7+9+x = 21+x. Mean = (21+x)/4 = 9. 21+x = 36, x = 15.

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