1.The average age of 8 children of a family is 12 yr. If the age of 7 children are 12, 8, 14, 11, 9, 13 and 15 yr, then the age of 8th child will be [RRB 2008]
Solution
Since total age of 8 children = 8 × 12
= 96 yr
and total age of 7 children
= 12 + 8 + 14 + 11 + 9 + 13 + 15
= 82 yr
Therefore the age of 8th children
= 96 - 82
= 14 yr
2. The ratio between the present ages of A and B is 4: 5. If the ratio between their ages 4 yr hence becomes 14:17, then what is B's age at present? [RRB 2009]
Solution
Let the ages of A and B are 4x and 5x respectively
A/Q, (4x + 4) / ( 5x + 4) = 14 / 17
68x + 68 = 70x + 56
2x = 12
x = 6
Therefore present age of B =5 × 6 = 30 yr
3. In a family, the average age of father and mother is 35 yr. The average age of the father, mother and their only son is 27 yr. What is the age of the son? [SSC CGL 2010]
Solution
Since total age of father and mother = 35 × 2
=70 yr
and total age of father, mother and son
= 27 × 3
= 81 yr
Therefore age of son = 81 - 70
= 11 yr
4.The average age of 9 students and their teacher is 16 yr. The average age of the first four students is 19 yr and that of the last five is 10 yr. The teacher's age is [SSC (10+2) 2010]
Solution
Since total age of 9 students and a teacher
= 10 × 16
= 160 yr
Total age of first 4 students = 4 × 19
= 76 yr
and total age of last 5 students = 5 × 10
= 50 yr
Therefore age teacher = 160 - 76 - 50
= 34 yr
5.At present, Anil is 1.5 times of Purvi's age. 8 yr hence, the respective ratio between Anil and Purvi's ages will be 25: 18 What is Purvi's present age? [IBPS Clerk 2011]
Solution
Let age of Purvi = x yr
Then age of Sunil = 1.5 x yr
According to the question
(1.5x + 8) / (x + 8) = 25 / 18
27x + 144 = 25x + 200
2x = 56
x = 28
Hence present age of Purvi = 28 yr
6.The average of the present ages of Sachin and Saurabh is 36 yr. If Sachin is 8 yr older than Saurabh, what is the Saurabh's present age? [Allahabad Bank Clerk 2010]
Solution
Since total age of Sachin and Saurabh
= 36 × 2
= 72
Let age of Saurabh = x yr
Then age of Sachin = x + 8
According to the question
x + x + 8 = 72
2x = 64
x = 32
Hence Saurabh's present age = 32 yr
7. At present Meena is eight times her daughter's age. 8 yr from now, the ratio of the ages of Meena and her daughter will be 10:3, respectively. What is Meena's present age? [IDBI PO 2009]
Solution
Let age of daughter = x yr
Age of Meena = 8x yr
According to the question
(8x + 8) / ( x + 8) = 10 / 3
24x + 24 = 10x + 80
14x = 56
x = 4
Hence Meena's present age = 4 × 8
= 32 yr
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