| 6. Talking about his neighbours, Ram says: "A is 5 times as old as B but his age is | 7 | of C's age. |
| 18 |
How much younger is B to C?
a. 27 years
b. 56 years
c. 83 years
d. Cannot be determined
Answer: c. 83 years
Explanation:
A's age = 5 times B's = 5B years
| Also, A's age | = | 7 | of C's age |
| 18 |
| ∴ C's age | = | 18 | of A's age = | 18 | x 5B = | 90B | years |
| 7 | 7 | 7 |
A's age + B's age + C's age = 132 -------------- Given
| ∴ 5B + B + | 90B | = 132 years |
| 7 |
∴ 35B + 7B + 90B = 132 x 7 --------------- Multiply by 7 on both sides
∴ B = 7 years
| C's age = | 90B | = 90 years |
| 7 |
B is (90 - 7 = 83) years younger than C
7. The average age of 4 children of a cricket class is 36 years. The youngest child amongst them is 6 years old. Find the average age of the group of 4 children when the youngest child was born?
a. 32 years
b. 36 years
c. 38 years
d. 40 years
Answer: d. 40 years
Explanation:
Present average age of the group = 36 years
Sum of present ages of all 4 children in the group = 36 x 4 = 144 years.
The youngest child is 6 years old, which means, the youngest was born 6 years ago.
So now, 6 years ago,
Sum of ages of all 4 children = 144 - (6 x 4) = 144 - 24 = 120 years
Since youngest one was just born, his age was 0.
So, now we should not include the youngest child in the group
So now, total number of children = 4-1=3
| Average age of group at time birth of the youngest child | = | Sum of ages of children |
| Number of children |
| ∴ Average age of group at time birth of the youngest child | = | 120 | = 40 years |
| 3 |
8. The average age of a family of 4 member, 4 years back was 19 years. Now, there's a new child added to the family and this has kept the average age of the family same. How old is the child recently added to the family?
a. 1 year
b. 2 years
c. 3 years
d. 4 years
Answer: c. 3 years
Explanation:
4 years back,
Average age of family = 19 years
Sum or Total of all ages of all 4 family members = 19 x 4 = 76 years
In present day, that means after 4 years,
Sum or Total of present ages of these 4 family members = 76 + (4 x 4) = 92 years.
Let the child's present age be K years.
Now family is of 5 members (because a child has been added some years back)
| Present average age of family | = | Sum of present ages of 4 members + Child's present age |
| 5 |
Average remains same as it was 4 years back
| ∴ 19 | = | 92+K |
| 5 |
∴ K = 3 years = This is the present age of the child.
9. Rohit's sister is 4 years younger to him. He got married 10 years back and his present age is 4/3 times his age at the time of marriage. Find the present age of his sister.
a. 26 years
b. 30 years
c. 34 years
d. 36 years
Answer: d. 36 years
10. Consider the following statements to answer the question given below:
i. The average age of two boys is five and a half years.
ii. If we find the average age of two boys and the father, it is 3 years more than the average age of boys with mother.
Find the age of father and mother.
a. 35 years and 32 years
b. 37 years and 28 years
c. 47 years and 38 years
d. 50 years and 41 years
Answer: a. 35 years and 32 years
