The average age of a group of friends is 27 years. If 4 new friends whose average age is 25 years join them, the average age of the entire group becomes 26 years. How many people were there in the group initially?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is Option 2 i.e. 4.
We know that,
Average = Sum of observations/Number of observations
Let's the initial number of friends in the group as "N"
The sum of the ages of the initial N friends = 27N
After 4 new friends join the group, the average age becomes 26 years
Now, the total sum of ages of the entire group after the 4 new friends join = 26(N + 4)
According to this question,
⇒ 27N + 4 × 25 = 26N + 104
⇒ 27N + 100 = 26N + 104
⇒ N + 100 = 104
⇒ N = 4
Initially, there were 4 friends in the group