Aptitude - Probability - Discussion
Discussion Forum : Probability - General Questions (Q.No. 13)
13.
Two cards are drawn together from a pack of 52 cards. The probability that one is a spade and one is a heart, is:
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 1 spade and 1 heart.
 n(E) |
= number of ways of choosing 1 spade out of 13 and 1 heart out of 13 |
| = (13C1 x 13C1) | |
| = (13 x 13) | |
| = 169. |
| P(E) = |
n(E) | = | 169 | = | 13 | . |
| n(S) | 1326 | 102 |
Discussion:
42 comments Page 1 of 5.
Kavitha said:
1 decade ago
Why can't it be (13C1 + 13C1) I am getting confused where 2 multiply and where 2 add can any one help me.
Parikshit said:
1 decade ago
The answer should be 13/51.
Both of the following two cases should be considered:
one is spade and the other is heart......and..
one is heart and the other is spade....
so multiply by 2..
Both of the following two cases should be considered:
one is spade and the other is heart......and..
one is heart and the other is spade....
so multiply by 2..
Probablity said:
1 decade ago
1st card is a spade = 13/52 AND
2nd card is a heart = 13/51
therefore 13/52 x 13/51 ... (1)
OR
1st card is a heart = 13/52 AND
2nd card is a spade = 13/51
therefore 13/52 x 13/51 ... (2)
Adding 1 & 2 we get 13/102
2nd card is a heart = 13/51
therefore 13/52 x 13/51 ... (1)
OR
1st card is a heart = 13/52 AND
2nd card is a spade = 13/51
therefore 13/52 x 13/51 ... (2)
Adding 1 & 2 we get 13/102
Mdk said:
1 decade ago
Thanks parikshit.
Swetha said:
1 decade ago
@kavitha.
In this question, we have to find propability for taking 2 cards one is spade and another one is heart. If and comes, we should multiply likewise if or is given, then we should add.
In this question, we have to find propability for taking 2 cards one is spade and another one is heart. If and comes, we should multiply likewise if or is given, then we should add.
Xyz said:
1 decade ago
@ kavita:
in case of "AND" we have to "multiply"
& in case of "OR" we have to "Add"
in case of "AND" we have to "multiply"
& in case of "OR" we have to "Add"
Santosh said:
1 decade ago
Here actually we discussed earlier as both are same combination we add other wise multiply. So clarify that doubt. I understood this problem but add and multiply explain.
Amol said:
1 decade ago
Thanks Probability
Neeta said:
1 decade ago
Can anybody explain me how to solve 52C2 ? or such other examples like 7C2, 13C1 etc.
Irfan said:
1 decade ago
52C2 = 52/2*51/1 i.e. 1326 Answer.
or
nCr = n!/(r!)(n - r)!
or
nCr = n!/(r!)(n - r)!
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