The average weight of 21 boys was recorded as 64 kgs. If the weight of the…
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The average weight of 21 boys was recorded as 64 kgs. If the weight of the teacher was added, the average increased by one kg. What was the teachers’ weight?
- A.
86 kgs
- B.
64 kgs
- C.
72 kgs
- D.
98 kgs
Attempted by 82 students.
Show answer & explanation
Correct answer: A
Solution: Find the teacher's weight by comparing the total weights before and after adding the teacher.
Total weight of 21 boys = 21 × 64 = 1344 kgs.
After adding the teacher the average becomes 65 kgs for 22 people, so total = 22 × 65 = 1430 kgs.
Teacher's weight = new total − original total = 1430 − 1344 = 86 kgs.
Answer: 86 kgs