NCERT Class XI Mathematics - Probability - Solutions
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Question : 45
Total: 54
A box contains 10 red marbles, 20 blue marbles and 30 green marbles.
5 marbles are drawn from the box, what is the probability that
(i) all will be blue?
(ii) atleast one will be green?
5 marbles are drawn from the box, what is the probability that
(i) all will be blue?
(ii) atleast one will be green?
Solution:
Here, total marbles = 10 + 20 + 30 = 60
We have to draw 5 marbles out of 60 marbles in
C 5
(i) There are 20 blue marbles.
We have to draw 5 marbles out of 20 blue marbles in
C 5
Thus, the probability that all will be blue =
(ii) There are 10 red marbles and 20 blue marbles.
We have to draw 5 marbles out of 30 marbles in
C 5
Thus, the probability that atleast one will be green = 1 −
We have to draw 5 marbles out of 60 marbles in
(i) There are 20 blue marbles.
We have to draw 5 marbles out of 20 blue marbles in
Thus, the probability that all will be blue =
(ii) There are 10 red marbles and 20 blue marbles.
We have to draw 5 marbles out of 30 marbles in
Thus, the probability that atleast one will be green = 1 −
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