A family consists of two grandparents, two parents and four children. Two years ago, the average age of the grandparents was 72 years. One year ago, the average age of parents was 36 years. At present, the average age of the children is 12 years. What is the present average age of the family?

33.75 years

ATQ,

Sum of grandparent's age, 2 years ago ⇒ 72×2 = 144

Sum of grandparent's present age ⇒ 144+4 = 148

Sum of parent's age, one year ago ⇒ 36×2 = 72

Sum of parent's present age ⇒ 72+2 = 74

Sum of children's present age ⇒ 12×4 = 48

Present average age of family ⇒ \(\frac{148+74+48}{8}\) = 33.75