8
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:

The ratio of Karthik’s and Kalyan’s ages is 4: 5. If the difference between the present age of Kalyan and the age of Karthik 5 years hence is 3 years, then what is the total of present ages of Karthik and Kalyan?

A) 56 years B) 62 years
C) 69 years D) 72 years
 
Answer & Explanation Answer: D) 72 years

Explanation:

Let us consider Karthik as K1 and Kalyan as K2.
Given 


and K2 - (K1 + 5) = 3
K2 - K1 = 8
K2 = 8 + K1
Now, 

 
K1 = 32 years
Therefore K2 = 40 years.
K1 + K2 = 72 years.

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4 77
Q:

Ten years ago, Kumar was thrice as old as Sailesh was but 10 years hence, he will be only twice as old. Find Kumar’s present age ?

A) 50 years B) 70 years
C) 60 years D) 40 years
 
Answer & Explanation Answer: B) 70 years

Explanation:

Let Kumar’s present age be "x" years and Sailesh’s present age be "y" years.
Then, according to the first condition,
x - 10 = 3(y - 10)  x - 3y = - 20 ........(1)
Now, Kumar’s age after 10 years = (x + 10) years.
Sailesh’s age after 10 years = (y + 10) years.
(x + 10) = 2 (y + 10)  x - 2y = 10 ......(2)

Solving (1) and (2),

we get x = 70 and y = 30


Kumar’s present age = 70 years    and

Sailesh’s present age = 30 years.

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4 65
Q:

Ten years ago, A was half of B in age. If the ratio of their present ages is 3:4, then what will be the total of their present ages?

Answer

Let A's age 10 years ago be x years . Then B's age 10 years ago be 2x years





 Total of their present ages = x + 10 + 2x + 10


= 3x+20


= 3 * 5 + 20 = 35 years


 

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4 302
Q:

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 number of boys to the number of girls in the class is

Answer

Suppose the number of boys and girls are x and y respectively





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4 1016
Q:

The ratio of the father's age to the son's age is 3 : 1. The product of their ages is 147. The ratio of their ages after 5 years will be?

Answer

Let father's age be 3x and son's age be x years




Father's age after 5 years = 3x + 5 = 26 years


Son's age after 5 years = x + 5 = 12 years


 Ratio of father's and son's ages = 26 : 12 = 13 : 6


 

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4 640