Average Questions

Use unitary method:

In  hours, 123 typists can type 984 paper

In 1 minute, 123 typists can type   = 246 papers

In 1 minute, 1 typist can type  =2 papers      [ Hint  hours = 4 minutes]

Clearly, we  have : x = (3y + 3z ) / 6 or 2x = y + z.

Let the number of boys = x

From the given data,

=> [21x + 16(18)]/(x+16) = 19

=> 21x - 19x = 19(16) - 16(18)

=> 2x = 16

=> x = 8

Therefore, the number of boys in the class = 8.

The third proportional of two numbers p and q is defined to be that number r such that

p : q = q : r.

Here, required third proportional of 10 & 20, and let it be 'a'

=> 10 : 20 = 20 : a

10a = 20 x 20

=> a = 40

Hence, third proportional of 10 & 20 is 40.

Since we know that the difference b/w the age of any two persons remains always constant, while the ratio of their ages gets changed as the time changes.

so, if the age of his child be x (presently)

Then the age of  wife be x + 26 (presently)

Thus the total age = x + ( x + 26) = 32  [∵252-220 =32]

=> x = 3

Therefore, The age of her child is 3 years and her self  is 29 years. Hence her age at the time of the birth of her child was 26 years.

Numbers of students in section A = x
∴ Numbers of students in section B and C = (100 – x)
∴ x 70 + (100 – x) 87.5 = 84 100
=> 70x + 87.5 100 – 87.5x = 8400
=> 8750 – 17.5x = 8400
=> 17.5x = 8750 – 8400 => x = 20.