## PROBABILITY(Set – 5)

1) There are some brown, black and red marbles in a packet out of which ‘x’ are
brown, 4 are black and ‘y’ are red. ‘y/2’ black marbles are added to the packet
and the probability of selecting a black marble becomes 4/13. Also, the average
of number of brown and red marbles in the packet is 9. What is the probability
of selecting 2 brown marbles before adding y/2 black marbles to the packet?

a) 15/77

b) 4/11

c) 17/93

d) 7/10

e) None of these

2) During a military parade, soldiers are asked to stand in a square formation
such that the number of soldiers each row and column is same. The probability
that a randomly selected soldier is on the edge of formation is 15/64. How many
soldiers are standing there in a row?

a) 15

b) 14

c) 17

d) 16

e) None of these

There are three bags A, B and C containing marbles of three different colors viz. Black, White and Grey.

Bag A: It contains a total of 36 marbles such that ratio of Black marbles and White marbles is 2:1 respectively, and probability of choosing two Grey marbles is 11/105.

Bag B:

The number of Grey marbles in bag B is the average of number of Black marbles and Grey marbles taken together in bag A. The probability of choosing a Black marble is 3/8 and the probability of choosing a White marble is 1/3.

Bag C:

Total number of balls in bag C is 1/2 of total number of balls in bag A and bag B taken together. The number of Black Marble in C is 25% less than that the number of white marbles in white bag B and the probability of choosing grey marble is 3/7.

1) ‘N’ number of Grey marbles are transferred from bag B to bag C and then
probability of choosing a Grey marble from bag C is 1/2. The value of ‘N’ is

a) 5

b) 6

c) 7

d) 8

e) 9

2) Two marbles are drawn from bag B one after another without replacement. Find the
probability that both the drawn marbles are white in color.

a) 5/47

b) 4/47

c) 7/94

d) 5/94

e) None Of these

3) Total number of marbles in Bag B?

a) 46

b) 44

c) 42

d) 48

e) None of these