The average age of a group is increased by 6 years when a person whose age is 24 years was replaced by a person whose age is 66. Find the number of persons in the group.
Answer & explanation
Correct answer: option 4
Lets assume average age of group = x
Number of people in group = n
⇒ \(\frac{ (nx - 24 + 66)}{n}\) = x + 6
⇒ nx + 42 = nx + 6n
⇒ n= 7
∴ Number of people in group are 7.