model 7 average on ages/weight Section-Wise Topic Notes With Detailed Explanation And Example Questions

Question : 1

From a class of 24 boys, a boy, aged 10 years, leaves the class and in his place a new boy is admitted. As a result, the average age of the class is increased by 2 months. What is the age of the new boy ?

a) 15 years

b) 12 years

c) 13 years

d) 14 years

Question : 2

The average age of 40 students of a class is 18 years. When 20 new students are admitted to the same class, the average age of the students of the class is increased by 6 months. The average age of newly admitted student is

a) 19 years 6 months

b) 19 years

c) 20 years 6 months

d) 20 years

Question : 3

In a class there are 30 boys and their average age is 17 years. On one boy aged 18 years leaving the class and another joining, the average age becomes 16.9 years. The age of new boy is

a) 11 years

b) 25 years

c) 15 years

d) 13 years

Question : 4

In a school with 600 students, the average age of the boys is 12 years and that of the girls is 11 years. If the average age of the school is 11 years and 9 months, then the number of girls in the school is

a) 150

b) 450

c) 350

d) 250

Question : 5

The average age of 9 students and their teacher is 16 years. The average age of the first four students is 19 years and that of the last five is 10 years. The teacher’s age is

a) 34 years

b) 36 years

c) 28 years

d) 30 years

Question : 6

In a family of 5 members, the average age at present is 33 years. The youngest member is 9 years old. The average age of the family just before the birth of the youngest member was

a) 29 years

b) 30 years

c) 24 years

d) 25 years