Question

3.the average age of twenty students is 12 years. if the teachers age is included, the average increases by one. what is the age of the teacher?

Explanation:

Step1: Find total age of students

The average age of 20 students is 12, so total age is \(20\times12 = 240\).

Step2: Find new average and total

After including teacher, number of people is 21, new average is \(12 + 1=13\). Total age now is \(21\times13 = 273\).

Step3: Calculate teacher's age

Subtract students' total from new total: \(273 - 240 = 33\).

Answer:

The age of the teacher is 33 years.