The average weight of 30 students is 60 kg. When the teacher's weight is included, the average becomes 61 kg.
What is the weight of the teacher?
Show answer & explanation
Correct answer: A
Explanation
Given:
Number of students = 30
Average weight of students = 60 kg
Average including teacher = 61 kg
Formula:
Total weight = Average × Number of people
Total weight of 30 students = 30 × 60 = 1800
Total weight of 31 people = 31 × 61 = 1891
Weight of teacher = 1891 − 1800 = 91 kg