Probability
Aptitude

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Q.

A bag contains 2 red, 3 green and 2 blue balls are to be drawn randomly. What is the probability that the balls drawn contain no blue ball?

 A.

5/7

 B.

10/21

 C.

2/7

 D.

11/21

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Solution:
Option(B) is correct

2 balls can be drawn in the following ways:

1 red, 1 green or 2 red or 2 green

Required probability: 

\(=\left(\dfrac{^2C_1\times ^3C_1}{^7C_2}\right)+\dfrac{^2C_2}{^7C_2}+\dfrac{^3C_2}{^7C_2}\)

\(=\dfrac{6}{21}+\dfrac{1}{21}+\dfrac{3}{21}\)

\(=\dfrac{10}{21}\)


(1) Comment(s)


VTG
 ()

there is no mention of 2 balls drawn in the question.Admin please correct.Thank you