The average age of a class of 30 students is 12 years. If the average age of 5 of these students is 10 years and another group of 5 is 14 years, then the average age of the remaining students is:
Answer & explanation
Correct answer: option 1
Average age of 30 students in a class = 12 years
5 students = 10 years
Another 5 students = 14 years
remaining student= 30 - 5 - 5 = 20
let's assume average age of 20 student = X
Total age of all student = average age x total no of student
30 x 12 = 5 x 10 + 5 x 14 + 20 x X
360 = 50 + 70 + 20X
360 = 120 + 20X
240 = 20X
X = 12years