Aptitude - Probability - Discussion
Discussion Forum : Probability - General Questions (Q.No. 2)
2.
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?
Answer: Option
Explanation:
Total number of balls = (2 + 3 + 2) = 7.
Let S be the sample space.
| Then, n(S) | = Number of ways of drawing 2 balls out of 7 | |||
| = 7C2 ` | ||||
|
||||
| = 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 | ||||
|
||||
| = 10. |
| P(E) = |
n(E) | = | 10 | . |
| n(S) | 21 |
Discussion:
116 comments Page 7 of 12.
Sathish kumar said:
1 decade ago
Total 7 balls.
Blue 2 balls.
So none of blue is 5 balls : 5c2/7c2.
(5x4/2x1)/(7x6/2x1) = 10/21 answer.
Blue 2 balls.
So none of blue is 5 balls : 5c2/7c2.
(5x4/2x1)/(7x6/2x1) = 10/21 answer.
Sundry said:
1 decade ago
From the explanation, where did 6 come from? why did you multiply 7 by 6? I did not understand that one.
Aarthi said:
2 decades ago
Can we do this n different method? finding the possibility that both are blue and finally ans-1.
Neha said:
1 decade ago
What is 3c2, 2c2 etc? could anyone please explain this whole sum according to a class 7 student.
Ritu verma said:
7 years ago
Prob of 1st ball not blue * prob of 2nd ball not blue.
= (5/7)*(4/6),
= 20/42,
= 10/21.
= (5/7)*(4/6),
= 20/42,
= 10/21.
Sarah said:
1 decade ago
The formula for ncr = n!/(n-r)!*r! if you submit values in this you can get the answer.
Aman said:
8 years ago
@Jaani.
What is the probability of picking 2 blue ball then what is the probability?
What is the probability of picking 2 blue ball then what is the probability?
Faffy said:
9 years ago
What if we use the tree diagrams because the way you answer is kindly complicated.
Gufran said:
5 years ago
(2R+3G)c2/7c2.
5c2/7c2.
5 * 2/2/7 * 6/2.
(20/2)/(42/2).
10/21 is the final answer
5c2/7c2.
5 * 2/2/7 * 6/2.
(20/2)/(42/2).
10/21 is the final answer
(1)
Nagen said:
1 decade ago
Whether sum of probability of 1 blue plus 2 blue is not opposite of none blue.
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