In a family of 5 members, the average age at present is 33 years. The youngest member is 9 years old. The average age of the family just before the birth of the youngest member was- 5 सदस्यो के एक परिवार में इस समय औसत आयु 33 वर्ष है। सबसे छोटा सदस्य 9 वर्ष का है। सबसे छोटे सदस्य के जन्म से तत्काल पूर्व परिवार की औसत आयु थी?

Current total age = 5 × 33 = 165 years. Youngest is 9 years old. Just before youngest's birth, family had 4 members and total age was 165 - 9 = 156 years (we subtract 9 years from everyone's current age, and the youngest didn't exist). Average = 156/4 = 39 years. But wait - we need to go back 9 years in time, so subtract 9×4 = 36 more years. Average = (156-36)/4 = 120/4 = 30 years.