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The average weight of 20 boys is 22.5 kg and that of 25 girls is 18 kg on a school bus. The average weight of all 45 students is equal to the 1/3rd of the weight of the bus driver. What is the change in the average weight of the bus including the driver if the old driver is changed with a new one whose weight is 6 kg more than the old driver?

The average weight of 20 boys is 22.5 kg and that of 25 girls is 18 kg on a school bus. The average weight of all 45 students is equal to the 1/3rd of the weight of the bus driver. What is the change in the average weight of the bus including the driver if the old driver is changed with a new one whose weight is 6 kg more than the old driver? Correct Answer 0.14 kg

Average = Sum of elements/Number of elements

Given,

Total weight of 20 boys in a bus = 20 × 22.5 = 450 kg

Total weight of 25 girls in a bus = 25 × 18 = 450 kg

Total weight of 45 students in a bus = 450 + 450 = 900 kg

Average weight of 45 students = 900/45 = 20 kg

Weight of  the driver = 20 × 3 = 60 kg

Average weight of bus including old driver = (900 + 60) / (45 + 1) = 20.86 kg

Weight of new driver = 60 + 6 = 66 kg

Average weight of bus including new driver = (900 + 66) / (45 + 1) = 21 kg

Change in the average weight of the bus = 0.14 kg

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