Question

There are 30 students in a class. The average age of the first 10 students is 12.5 years. The average age of the remaining 20 students is 13.1 years. The average age (in years) of the students of the whole class is:

• A. 12.5 years
• B. 12.7 years
• C. 12.8 years
• D. 12.9 years

Answer 1

Answer:

D. 12.9 years

Total age of first 10 students = (10 × 12.5) years = 125 years. Total age of remaining 20 students = (20 × 13.1) years = 262 years. Age of whole class = 125 + 262 = 387 years. Total students = 30 Average age of class = 387/30 = 12.9 years.