Question

A group of 20 students attempting a MathematicalChallenge have an average age of 11. When their teacher is included their average age is12. What is the age of the teacher?

Answer 1

32.

1st get the total age of the students

x/20 = 11

x=11x20

x =220 (total age of students)

add y ( teachers age) to the equation

(220 + y)/21=12

y= 32

Answer 2

32

Explanation:

20 * 11= 220

21 * 12= 252

252-220=32