Act 300 - Averages

3 years ago, the average of a family of 5 members was 17 years. A baby having been born, the average age of the family is the same today. The present age of the baby is:

                   

• 5 years

• 2 years

• 1 year   

• 4 years

Of the four numbers, the first is twice the second, the second is one-third of the third and the third is 5 times the fourth. The average of the numbers is 24.75. The largest of these numbers is:

    

• 40

• 25

• 30

• 45

The average age of students of a class is 15.8 years. The average age of boys in the class is 16.4 years and that of the girls is 15.4 years. The ratio of the number of boys to the number of girls in the class is:

        

• 1:4

• 2:3

• 3:4

• 4:2

The average price of 10 books is Rs. 12 while the average price of 8 of these books is Rs. 11.75. Of the remaining two books, if the price of one book is 60% more than the price of the other, what is the price of each of these two books?

• Rs 10 and Rs 16

• Rs 12 and Rs 24

• Rs 24 and Rs 18  

• Rs 28 and Rs 12

The average age of 30 boys of a class is equal to 14 years. When the age of the class teacher is included the average becomes 15 years. Find the age of the class teacher?

    

• 50

• 44

• 45

• 42

The Average of marks obtained by 120 candidates in a certain examination is 35. If the average marks of passed candidates is 39 and that of failed candidates is 15, what is the number of candidates who passed the examination?

      

• 90

• 100

• 108

• 115

The average of 11 results is 50. If the average of first 6 results is 49 and that of last 6is 52, find the sixth result?      

• 55

• 56

• 65

• 62

The average age of a family of 6 members is 22 years. If the age of the youngest member be 7 years, then what was the average age of the family at the birth of the youngest member?      

• 15

• 18

• 28

• 24

A batsman in his 17th innings makes a score of 85, and thereby increases his average by 3. What is his average after 17 innings?

        

• 30

• 37

• 40

• 45

There were 35 students in a hostel. If the number of students increase by 7, the expenses of the mess increase by Rs 42 per day while the average expenditure per head diminishes by Rs 1. Find the original expenditure of the mess?

       

• 450

• 420

• 430

• 410