Aptitude - Probability - Discussion

Discussion Forum : Probability - General Questions (Q.No. 12)
12.
A bag contains 4 white, 5 red and 6 blue balls. Three balls are drawn at random from the bag. The probability that all of them are red, is:
1
22
3
22
2
91
2
77
Answer: Option
Explanation:

Let S be the sample space.

Then, n(S) = number of ways of drawing 3 balls out of 15
= 15C3
= (15 x 14 x 13)
(3 x 2 x 1)
= 455.

Let E = event of getting all the 3 red balls.

n(E) = 5C3 = 5C2 = (5 x 4) = 10.
(2 x 1)

P(E) = n(E) = 10 = 2 .
n(S) 455 91

Discussion:
33 comments Page 2 of 4.

Sinchana said:   6 years ago
If the answer is 0.02 something how we can convert please explain it now.
(1)

Akanksha said:   6 years ago
A box contains 6000 cards numbered 1 to 6000. One card is drawn at random from the box. Find the probability that the number is neither divisible by 4 nor 6? Please give me a solution.
(1)

Shiva said:   7 years ago
Why not 3/5 for selecting 3 red balls from total 5 red balls?
(1)

Rahul. Moorkoth said:   7 years ago
According to me, the Answer should be 4/91.
(1)

Somya said:   8 years ago
While calculating the term for red balls, why did we not consider the blue balls?

Adu said:   8 years ago
Thanks all.

Chetan said:   8 years ago
Good explanation, Thanks @Rohit.

Pandu raju said:   9 years ago
Thank you for the explanation.

Alab said:   9 years ago
4 + 5 + 6 = 15.

First draw is 5/15.
Second 4/14.
Third 3/13.

(5/15)(4/14)(3/13) = 2/91
(1)

Hiren said:   9 years ago
I like your logic @Dharika.


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