Multiple choice

If arithmetic mean of 7, 8, 11, 16, x, 15 and 13 is 12, then the value of x is equal to __________.

  1. 10

  2. 11

  3. 12

  4. 14
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D Correct answer
Explanation

Sum of numbers = 7 + 8 + 11 + 16 + x + 15 + 13 = 70 + x. Mean = (70 + x) / 7 = 12. 70 + x = 84, so x = 14.

AI explanation

The arithmetic mean formula dictates that the sum of the observations equals the mean multiplied by the total number of observations. The total sum is 7 times 12, which equals 84. Adding the known values gives 7 + 8 + 11 + 16 + 15 + 13 = 70. Setting this sum plus x equal to the total gives 70 + x = 84, so x = 14. The result is 14.

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