Question

In a class there are total 70 students. The average weight of 26 girls is 28 kg and average weight of the remaining students is 35 kg. What will be the average weight (in kg) of all 70 students?

• A. 32.4 kg
• B. 36.8 kg
• C. 35.2 kg
• D. 34.6 kg

Answer 1

Answer:

A. 32.4 kg

Solution: Given: Total number of students = 70 The average weight of 26 girls is 28 kg The average weight of the remaining students is 35 kg Formula used: Average weight = Total weight/Number of students Calculation: The average weight of 26 girls is 28 kg ⇒ Total weight of 26 girls = 26 × 28 = 728 The average weight of the remaining students is 35 kg The number of remaining students = 70 - 26 = 44 (∵ Total number of students = 70) ⇒ Total weight of 44 girls = 44 × 35 = 1540 Total weight of 70 students = Total weight of 26 girls + Total weight of 44 girls ⇒ Total weight of 70 students = 728 + 1540 = 2268 ∴ Average weight of 70 students = 2268/70 = 32.4 kg Short Trick: Average weight of 70 students = [26 × 28 + (70 - 26) × 35]/70 ∴ required average = 32.4 kg