The average age of 40 students in a class is 12 years. The average age of the students increased by 4 months due to 20 new admissions in the class. The average age of the newly admitted students is:
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 13 years.
Average age of 40 students = 12 years
New average after 20 admissions = 12 years + 4 months = 12.33 years (since 4 months = 1/3 year)
Total students = 40 + 20 = 60
Total age after admissions = 60 × 12.33 = 739.8 years
Total age before admissions = 40 × 12 = 480 years
Age of 20 new students = 739.8 − 480 = 259.8 years
Average age of new students = 259.8 ÷ 20 = 12.99 years ≈ 13 years