The mean age of R men in a club is 50 years, Two men aged 55 and 63, left the club and the mean age reduced by 1 year. Find the value of R
-
A.
18 -
B.
20 -
C.
22 -
D.
28
Correct Answer: Option B
Explanation
mean age = (frac{text{sum of ages}}{text{no. of men}})
50 = 9frac{sum}{R})
sum = 50R…..(1)
Sum of ages of the men that left = 55 + 63 = 188
remaining sum = 50R – 118
remaining no. of men = R – 2
now mean age = 50 – 1 = 49 years
49 = (frac{50R – 118}{R – 2})
49(R – 2) = 50R – 118
49R – 50R = -188 – 98
-R = -20
R = 20