The mean of twelve positive numbers is 3. When another number is added, the mean becomes 5. Find the thirteenth number
-
A.
29 -
B.
26 -
C.
25 -
D.
24
Correct Answer: Option A
Explanation
Let the sum of the 12 numbers be x and the 13th number be y.
(frac{x}{12} = 3 implies x = 36)
(frac{36 + y}{13} = 5 implies 36 + y = 65)
(y = 65 – 36 = 29)