Answer: Option C
Answer: (c)Overall increase in the total age = 8 × 2 = 16 years ∴ Total age of two new men = 21 + 23 + 16 = 60 years ∴ Average age of new men = $60/2$ = 30 yearsAliter : Using Rule 23, ( If in a group, one member is replaced by a new member, then, Age of new member = ( age of replaced member) ± xn where, x = increase (+) or decrease (–) in average n = Number of members. )Here, x = 2, n = 8 Age of new person = Age of replaced person + x = 24 + 2 × 8 = 24 + 16 = 40 years