A scholar was asked to find the arithmetic mean of the numbers 4, 11, 7, 9, 16, 13, 8, 19, 18, 21, 12 and x. He found the mean to be 12. What should be the number in place of x?
Show answer & explanation
Correct answer: C
Explanation
Total numbers = 12
Mean = 12
Therefore, the total sum = 12 × 12 = 144
Sum of the given 11 numbers = 4 + 11 + 7 + 9 + 16 + 13 + 8 + 19 + 18 + 21 + 12
= 138
138 + x = 144
x = 144 - 138
x = 6