Question
The average weight of 20 students in a class is 50 kg.
If the weight of the teacher is included, the average weight increases by 1 kg. If the weight of the teacher is excluded and replaced with another student weighing 55 kg, what will be the new average weight of the group?Solution
Total weight of 20 students = 20 × 50 = 1,000 kg Including the teacher, new total weight = 21 × 51 = 1,071 kg Teacher’s weight = 1,071 - 1,000 = 71 kg Replacing the teacher with a 55 kg student: New total weight = 1,000 + 55 = 1,055 kg New average = 1,055 ÷ 21 = 50.24 kg Correct Option: a)
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