Table of Contents
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
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