Question

Which number is to be added to the given set of numbers so that mean of the new set becomes 6?
3 , 7 , 8 , 9 , 3 , 4 , 5, 1

• A. 10
• B. 12
• C. 13
• D. 14

Answer 1

The correct option is D 14

Given set of numbers: 3 , 7 , 8 , 9 , 3 , 4 , 5, 1
Let $x$ be the number that is to be added to this set so that the new mean equals 6.
Then, $\frac{3+7+8+9+3+4+5+1+x}{9}=6$
$⟹40+x=54$
$⟹x=14$
Thus, the number to be added to the old set so that the new mean equals 6 is 14.