Question
In a school, there are 20 teachers. The average age of
all the teachers is 40 years. If the age of three principals is included, then the average age is increased by 3 years. Find the average age of three principals.Solution
ATQ, Average age of 20 teachers = 40 years Sum of the ages of 20 teachers = 40 × 20 = 800 After including the age of 3 principals, new average age = 43 years Sum of the ages of 20 teachers including principals = 43 × 23 = 989 Sum of the ages of 3 principals = 989 – 800 = 189 Average age of 3 principals = 189/3 = 63 years
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