8%
10.50%
11.20%
12.80%
Answer is Wrong!
Answer is Right!
The correct answer is (b) 10.5%.
The total age of the family is 19 * 4 = 76 years.
After two years, the total age of the family will be 76 + 2 * 4 = 84 years.
The average age of the family after two years will be 84 / 4 = 21 years.
The percentage increase in average age is (21 – 19) / 19 * 100 = 10.5%.
Option (a) is incorrect because 8% is the percentage increase in the total age of the family, not the average age.
Option (c) is incorrect because 11.2% is the percentage increase in the average age if the total age of the family is 80 years.
Option (d) is incorrect because 12.8% is the percentage increase in the average age if the total age of the family is 84 years.