Question

At present the average age of 20 students of class ten is 15.5 years. The present age of the class teacher is 47 years. What will be the average age of the students and the class teacher

• A. 20
• B. 17
• C. 22
• D. 40

Answer 1

Answer:

B. 17

Step-by-Step Calculation for the Given Problem

• Initial Scenario: We have 20 students, and their average age is 15.5 years.

• Step 1: Calculate the total age of the 20 students.

  • Total Age = Average Age × Number of Students

  • Total Age = 15.5 years × 20 = 310 years.

• Step 2: Include the class teacher's age.

  • The class teacher's age is 47 years.

  • When the teacher joins, the total number of people becomes 20 (students) + 1 (teacher) = 21 people.

• Step 3: Calculate the new total age of students and the teacher.

  • New Total Age = Total age of students + Teacher's age

  • New Total Age = 310 years + 47 years = 357 years.

• Step 4: Calculate the new average age.

  • New Average Age = (New Total Age) / (New Number of People)

  • New Average Age = 357 years / 21 = 17 years.