Discussion :: Probability
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A bag contains 2 red, 3 green and 2 blue balls. Two balls are drawn at random. What is the probability that none of the balls drawn is blue?
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A.
\(\frac { 10 } { 2 1}\) |
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B.
\( \frac { 11 } { 2 1} \) |
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C.
\( \frac { 2} { 7 } \) |
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D.
\( \frac { 5} { 7 } \) |
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Answer : Option A
Explanation :
Total number of balls = (2 + 3 + 2) = 7.
Let S be the sample space.
Then,= Number of ways of drawing 2 balls out of 7
= 7c2
=\(\frac { (7*6) } { (2 *1)} \)
= 21
Let E = Event of drawing 2 balls, none of which is blue.
n(E)Number of ways of drawing 2 balls out of (2 + 3) balls
=5C2
= \(\frac { (5*4) } { (2 *1)} \)
=10
P (E) =\(\frac { n (E)} {n(s)}\)= \(\frac { 10 } { 2 1}\)
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