Eight persons with an average weight of 49 kg were in a lift. Two more persons, Anita and Kamal, boarded the lift and the average weight of the persons in the lift increased by 2.8 kg. What is the average weight of Anita and Kamal?
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 63 kg
Total weight = average × number of persons. The two new persons’ weight is the rise in the total when they board.
Total of the 8 persons \(=8\times49=392\) kg
New average \(=49+2.8=51.8\) kg, so the total of the 10 persons \(=10\times51.8=518\) kg
Anita and Kamal together \(=518-392=126\) kg
Their average \(=\frac{126}{2}=63\) kg
Shortcut: The two newcomers must bring the old average for themselves and also lift all 10 persons by 2.8 kg.
Extra weight needed \(=10\times2.8=28\) kg
Their total \(=2\times49+28=126\) kg, an average of 63 kg