A class has 20 boys and 20 girls. The average age of girls in the class is 16 years and the average age of boys in the class is 17 years. One girl and one boy leave the class and the average age of the girls reduced by 1 year and that of boys reduced by 2 years. Find the new average age of the whole class.
1
15 years
2
22 years
3
10.5 years
4
20 years