Single correct option
The average weight of 8 students in a group is 52 kg. When a new student joins the group, the average weight increases by 1.5 kg. Find the weight of the new student (in kg).
- A. 61.5
- B. 63.5
- C. 65.5
- D. 67.5
Show answer and solution
Answer: (C) 65.5
Original total weight = 8 × 52 = 416 kg. New average = 53.5 kg over 9 students, so new total = 9 × 53.5 = 481.5 kg. Weight of new student = 481.5 − 416 = 65.5 kg. Shortcut: new student's weight = old average + (increase × new number of people) = 52 + 1.5×9 = 65.5 kg.
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