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Q:

The average age of a group of 10 students is 15 years. When 5 more students join the group, the average age increase by 1 year. The average age of the new students is? 

Answer:
Q:

Two boys are playing on a ground. Both the boys are less than 10 years old. Age of the younger boy is equal to the cube root of the product of the age of the two boys. If we place the digit representing the age of the younger boy to the left of the digit representing the age of the elder boy, we get the age of the father of the younger boy. Similarly, we place the digit representing the age of the elder boy to the left of the digit representing the age of the younger boy and divide the figure by 2, we get the age of the mother of the younger boy. The mother of the younger boy is younger than his father by 3 years. Then, what are the ages of elder and younger boys ?

A) E = 15 & Y = 3 B) E = 14 & Y = 12
C) E = 40 & Y = 22 D) E = 4 & Y = 2
 
Answer & Explanation Answer: D) E = 4 & Y = 2

Explanation:

Let the the age of the elder boy = E

Let the the age of the younger boy = Y

Given that Y = cube root of EY


=>  = EY => E =  .....(1)
By the condition of number replacement the age of the father is YE

The Mother's age = EY/2

But she is 3 years less than father => EY/2 + 3 = YE
2YE = EY + 6 ......(2)

Then now from the given options we can identify which satisfies the all the conditions.

Here Y =2 and E = 4 satisfies all the conditions.

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1 0
Q:

5 years ago Sushma was 5 times as old as her Son. 5 years hence her age will be 8 less than three times the corresponding age of her Son. Find their ages ?

A) 24 and 13 years B) 48 and 24 years
C) 35 and 11 years D) 33 and 15 years
 
Answer & Explanation Answer: C) 35 and 11 years

Explanation:

Let the age of sushma be x and
the age of her son is y
Then five years before x-5=5(y-5) ...(1)
Five years hence x+5 = 3(y+5)-8 .....(2)

By soving (1) & (2), we get
5y - 15 = 3y + 7
y = 11 => x = 35

Therefore, the age of Sushma = 35 and her son = 11.

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1 1
Q:

The ratio of present ages of X and Y is 4:5. Which of the following can't be the ratio of ages of X and Y, 20 years ago ?

A) 2 : 5 B) 8 : 15
C) 9 : 10 D) 3 : 5
 
Answer & Explanation Answer: C) 9 : 10

Explanation:

The ratio of X and Y ages at present is 4:5. 

Then, the ratio 20 years ago will not be more than the ratio at present.

So, from the options 9:10 is not satifying => its ratio is 0.9 which is greater than presnt ratio of 0.8.

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1 4
Q:

The average of the ages of Sushanth, Krish and Rishi is 43 years and the average of the ages of Sushanth, Rishi and Rohit is 49 years. If Rohit is 54 years old, what is Krish's age ?

A) 34 years B) 26 years
C) 24 years D) 36 years
 
Answer & Explanation Answer: D) 36 years

Explanation:

Let present ages of Sushanth = w, Krish = x, Rishi = y and Rohit = z , then
w + x + y = 43 x 3 = 129 ---(i) and
w + y + z = 49 x 3 = 147 ---(ii)
Subtracting (i) from (ii), (w+y+z) - (w+x+y) = 147 - 129 , z - x = 18 ---(iii)
Given Rohit's age=z=54, so from (iii), x = 54 - 18 = 36.
Therefore, Krish age is 36 years.

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3 18
Q:

On a ruler's tombstone, it is said that one sixth of his life was spent in childhood and one twelfth as a teenager. One seventh of his life passed between the time he became an adult and the time he married; five years later, his son was born. Alas, the son died four years before he did. He lived to be twice as old as his son did. How old did the ruler live to be ?

A) 84 years B) 72 years
C) 82 years D) 64 years
 
Answer & Explanation Answer: A) 84 years

Explanation:

Let the age of ruler is x so that of son = x/2 (given)
Now according to the given condition
(x/6) + (x/12) + (x/7) + 5 + (x/2) + 4 = x
=> x = 84

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