Aptitude - Probability - Discussion

Discussion Forum : Probability - General Questions (Q.No. 9)
9.
From a pack of 52 cards, two cards are drawn together at random. What is the probability of both the cards being kings?
1
15
25
57
35
256
1
221
Answer: Option
Explanation:

Let S be the sample space.

Then, n(S) = 52C2 = (52 x 51) = 1326.
(2 x 1)

Let E = event of getting 2 kings out of 4.

n(E) = 4C2 = (4 x 3) = 6.
(2 x 1)

P(E) = n(E) = 6 = 1 .
n(S) 1326 221

Discussion:
32 comments Page 3 of 4.

Lola said:   1 decade ago
The n(k) = 4, so the p(getting a king)=4c1, or 4/52 : p(getting 2 king) = 4c2. NB: combination mean selection.

Jhansi sri said:   1 decade ago
How can we know the cards are only kings in 52. In 4 kings we take 2 only so we take 4p2. Please help me?

Naveenaa said:   9 years ago
Could anyone kindly clarify at what type of situations we are about to use this nCn?

Alok said:   3 years ago
As drawing of cards are dependent events, I think 4c1*3c1/52c2 will be correct.
(1)

Vinayak said:   8 years ago
There are 12 kings in 52 cards.
Then how to use 4 out 2.
There is 12 out of 2.

Ajith kumar said:   1 decade ago
@ Shyam

Generally there are only four kings in a pack of 52 cards.

S.Mounica said:   1 decade ago
Its formula, nC2 = n*n-1/1*2

So we get it.

Prince said:   1 decade ago
(52 x 51)
---------..? how is this equation possible..?
(2 x 1)

Rahul said:   6 years ago
Shouldn't it be 8C2 instead of 4C2? as two packs have 8 kings.
(1)

Mahi said:   9 years ago
Prince.

Formula for nCr = n!/(n-r)!/r!


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