EXERCISE 6.A (OBJECTIVE TYPE QUESTIONS) (IN 76 80 SOLUTION)

76.       3 years ago, the average age 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

a)      1 year

b)      1 ½ years

c)       2 years

d)      3 years.

77.       10 years ago, the average age of a family of 4 members was 24 years. Two children having been born (with age difference of 2 years), the present average age of the family is the same. The present age of the  youngest child is:

a)      1 years

b)      2 years

c)       3 years

d)      5 years

78.       After replacing an old member by a new member by a new member, it was found that the average age of five members of a club is the same as it was 3 years ago. What is the difference between the ages of their placed and the new members.

a)      2 years

b)      4 years

c)       8 years

d)      15 years.

79.       The average age of 3 children in a family is 20% of the average age of the father and the eldest child. The total age of the mother and the youngest child is 39years. If the father’s age is 26 years, what is the age of second child?

a)      15 years

b)      18 years

c)       20 years

d)      Cannot be determined

80.       The average age of a group of persons going for picnic is 16 years. Twenty new persons with an average age of 15 years join the group of the sport due to which their average age becomes 15.5 years. The number of persons initially going for picnic is:

a)      5

b)      10

c)       20

d)      30

ANSWERS

76.C

77.C

78.D

79.D

80.C

SOLUTION

76.       Total age of 5 member, 3 years ago = (17 x 5) years = 85 years.

Total age of 5 members now = (85 + 3 x 5) years = 100 years.

Total age of 6 members now = (17 x 6) years = 102 years.

Age of the baby = (102 – 100) years = 2 years.

77.       Total age of 4 members, 10 years ago = (24 x 4) years = 96 years.

Total age of 4 members now = (96 + 10 x 4) years = 136 years.

Total age of 6 members now = (24 x 6 ) years = 144 years.

Sum of the ages of 2 children = (144 – 136) years = 8 years.

Let the ager of the younger child be x years.

Then, age of the elder child = (x + 2) years.

So, x + X + 2 = 8  2x = 6  X = 3.

Age of younger child = 3 years.

78.       Age decreased = (5 x 3) years = 15 years.

So, the required difference = 15 years.

79.       Since the total or average age of all the family members is not given, the given data is inadequate, so, the age of second child cannot be determined.

80.       Let the initial number of persons be x. then,

16x + 20 x 15 = 15.5 ( x + 20)  0.5 x = 10   x = 20.