The average age of 8 men rises by 2 years when two of them, aged 21 and 23, are replaced by two women. What is the average age of the two women?

Explanation

1. 01

   The total age rises by $8 \times 2 = 16$ years.

2. 02

   The women's total = $21 + 23 + 16 = 60$ years.

3. 03

   Their average = $\frac{60}{2} = 30$ years.