Quantitative Aptitude - Arithmetic Ability Questions

Given a secret is told to 3 persons in 3 minutes.
And if the process continues with each person saying 3 other persons,
In 30 minutes => the rocess for 10 times because each person time is 3 minutes.
Required number of persons = 3 + 32 + 33 + .... + 39 + 310

Now it forms a geometric progression,

Sum to n terms is S = arn - 1r - 1

Here a = 3, r = 3

 
=> 59048 x 3 /2

= 88572.

In a family with 2 children there are four possibilities:
1) the first child is a boy and the second child is a boy (bb)
2) the first child is a boy and the second child is a girl (bg)
3) the first child is a girl and the second child is a boy (gb)
4) the first child is a girl and the second child is a girl (gg)

But already given that one child is boy. So we have three possibilities of (bb)(bg)(gb).
n(E)= both are boys=BB=1
n(S)= 3
Required probability P = n(E)/n(S) = 1/3.

Probability of not hitting the ball = 1- 1/4 =
Then, the probability that the batsman will hit the ball =

SP of first article = 1000
Profit = 30%
CP = (SP)x[100/(100+P)] = 10000/13

SP of second article = 1000
Loss = 20%
CP = (SP)x[100/(100-L)] = 5000/4 = 1250

Total SP = 2000

Total CP = 10000/13 + 1250 = 2019.23

CP is more than SP, he makes a loss.

Loss = CP-SP = 2019.23 - 2000 = 19.23
Loss Percent = [(19.23)/(2019.23)]x100 = 0.95 %.

Present age of Sony = 24 + 4 = 28 years

After 5 years Renuka's age = 7×5 + 5 = 40 years

Number of books that can be placed in the larger box is given by Volume of Box / Volume of book.
Now, n = 25 x 42 x 60 / 7 x 6 x 5
= 63000 / 210
= 300.
Therefore, 300 books can be in that box.