The average age of a family of 5 members is 20 years. The youngest member is…
2013
The average age of a family of 5 members is 20 years. The youngest member is 10 years old. What was the average age of the family when the youngest member was born?
Answer: C. 12 years 6 months 12 — Step 1: Calculate the total current age of the family. Since the average age is 20 years for 5 members, the total age is 5 × 20 = 100 years. Step 2: The…
- A.
10 years
10 वर्ष
- B.
10 years 6 months 10
- C.
12 years 6 months 12
- D.
8 years
8 वर्ष
Attempted by 5 students.
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Correct answer: C
Step 1: Calculate the total current age of the family. Since the average age is 20 years for 5 members, the total age is 5 × 20 = 100 years.
Step 2: The youngest member is 10 years old, so 10 years ago, when they were born, the total age of the family was 100 - (5 × 10) = 50 years. This accounts for the age increase of all 5 members over 10 years.
Step 3: At that time, the youngest member was not yet born, so there were only 4 members in the family.
Step 4: Calculate the average age of the 4 members at that time: 50 ÷ 4 = 12.5 years, which is 12 years 6 months.
हिन्दी उत्तर:
चरण 1: परिवार की कुल वर्तमान आयु गणना करें। 5 सदस्यों की औसत आयु 20 वर्ष है, इसलिए कुल आयु 5 × 20 = 100 वर्ष है।
चरण 2: सबसे छोटा सदस्य 10 वर्ष का है, इसलिए 10 साल पहले, जब वह पैदा हुआ था, परिवार की कुल आयु 100 - (5 × 10) = 50 वर्ष थी। यह 10 साल में सभी 5 सदस्यों की आयु वृद्धि को ध्यान में रखता है।
चरण 3: उस समय, सबसे छोटा सदस्य अभी तक पैदा नहीं हुआ था, इसलिए परिवार में केवल 4 सदस्य थे।
चरण 4: उस समय 4 सदस्यों की औसत आयु गणना करें: 50 ÷ 4 = 12.5 वर्ष, जो 12 वर्ष 6 महीने है।