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.
Manoj said:
9 years ago
How did you obtain 21 sample spaces in the above-mentioned solution?
Can you mention all possible combination of balls?
Ex:{ HH, TT, HT, TH } for 2coins.
Can you mention all possible combination of balls?
Ex:{ HH, TT, HT, TH } for 2coins.
NAMRA shah said:
9 years ago
Not understanding, please Explain me this method.
Manisha said:
9 years ago
Please solve this question:
A bank contains 5white,6red,2green, and 2black balls one ball is selected at random from the bag. Find the probability that the selected ball is:
1. White
2. Non white
3. White or green
4. Black or red
A bank contains 5white,6red,2green, and 2black balls one ball is selected at random from the bag. Find the probability that the selected ball is:
1. White
2. Non white
3. White or green
4. Black or red
Pooja said:
9 years ago
Please solve this question:
A bag contains 5 white, 6 red, 2 green and 2 black balls. One ball is selected at random from the bag. Find the probability that the selected ball is;
A) white
B) non-white
C) white or green
D) black or red
A bag contains 5 white, 6 red, 2 green and 2 black balls. One ball is selected at random from the bag. Find the probability that the selected ball is;
A) white
B) non-white
C) white or green
D) black or red
Saravana said:
9 years ago
What is the need for finding the first step? Please Explain.
Shah Rukh said:
9 years ago
@Pooja for A. White.
Ans = totql balls = 5+6+2+2 = 15.
Totql no. Of outcomes i.e. S=15c1 =15/1 = 15.
Event A = 5c1 = 5.
Probability of event A = 5/15 = 1/3.
Ans = totql balls = 5+6+2+2 = 15.
Totql no. Of outcomes i.e. S=15c1 =15/1 = 15.
Event A = 5c1 = 5.
Probability of event A = 5/15 = 1/3.
ASHUTOSH said:
9 years ago
Why not the answer is 5/7?
Abic said:
9 years ago
The probability of getting blue is 2/7.
If we sub 1-2/7 the answer is 5/7 why it is inaccurate? Please explain me.
If we sub 1-2/7 the answer is 5/7 why it is inaccurate? Please explain me.
Sathya said:
9 years ago
Here, using combination formulae is good so the answer is 11/21 is correct.
Solution:.
First possibility 3 balls 7c2 = 21.
Second possibility is 5c2 = 11.
So that the answer is=11/21.
Solution:.
First possibility 3 balls 7c2 = 21.
Second possibility is 5c2 = 11.
So that the answer is=11/21.
Laura said:
8 years ago
How 7x6?
where did you get the 6 from?
Please explain it in detail.
where did you get the 6 from?
Please explain it in detail.
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