Q. The average age of a teacher and three students is 20 years. If all the three students are of same age and the difference between the age of the teacher and each student is 20 years, then what is the age of the teacher?

Explanation :

Average age of a teacher and 3 students is 20

Given information:
– Average age of teacher and 3 students = 20 years
– All students are of same age
– Difference between teacher’s age and each student’s age = 20 years

Solution:
1. Sum of ages = Average age × Number of people
= 20 × 4 = 80 years

2. Let student’s age = x
Then, teacher’s age = x + 20

3. Equation:
3x + (x + 20) = 80
4x + 20 = 80
4x = 60
x = 15

Therefore:
– Each student’s age = 15 years
– Teacher’s age = 15 + 20 = 35 years