A) 20 yr
B) 16 yr
C) 12 yr
D) 18 yr
E) 21yr
Correct Answer: A
$ \therefore $ Total age of five members of a family $ =24\times 5=120 $
$ \therefore $ Total age of four members at the time of birth of the youngest member $ =120-8\times 5 $ $ =120-40=80yr $ Hence, required average age $ =\frac{80}{4}=20yr $