Aptitude - Probability - Discussion

See actually only one queen is there in club and only one king in heart therefore it will be : 1C1+1C1=2.

2/52=1/26.

According to me, club And Heart contain 13, 13 cards. Given 1 queen in club or 1 king in heart. So the answer is n(s) =1.

And n(E) = 26. So p(E) =n(E) /n(s) = 1/26.

(4C1 X 4C1)/52C1

what is the error in this method? Why cant I follow this method?


I know i'm wrong, but please clarify my doubt...
Thanking you..

Hi, if asked as queen of club and king of heart, then can we do in this method
(13/26)*(12/25).

Here 1 queen of club selected so 13/26 and 1 king of heart selected so 12/25 Because already one is selected now they are the remaining.

Total cards 52c1.

So answer would be (13/26)*(12/25).

= 6/25.

So answer is (6/25)/52C1 = 312/25.

Here's a simple way. I hope it helps:

Sample space is 52.

Now, in the entire pack of cards, only two cards satisfy the given condition of being either king of hearts of queen of clubs. Therefore, event space = 2
Probability = S/E = 2/52 = 1/26.

In the question they specified that OR(+) so in the numerator we have 2 only.

In question, the term used is 'or', then how the probability of event became 2. (i.e, n (E) =2) ?

We have 1 queen of club and 1 queen of heart so,

[1C1(containing queen of club)+1c1(containing king of heart )]/52C1

[1+1]/52= 2/52=>1/26.


@Sajna. Simply "OR" means "addition" and "AND" means "MULTIPLICATION". Out of 52 cards we have only 1 queen of club and 1 king of heart. [1+1]/52.

By or we mean either a king of heart or a queen of clubs, so p(king of heart)=1/52=p(queen of clubs) and n(e)=2, So p=2/52=1/26.

Guys, please try my solution.

The formula for probability is :

P(E) = n(E)/n(S).

Here, P(E) = probability of an event.
n(E) = total no.of drawn cards.
n(S) = total no.of cards.

Here, n(E) = 1 = total no.of drawn cards.
( because only one card is drawn from a pack of
52 cards.)
n(S) = 52 = total no.of cards.
(because total no.of cards we have 52.).

Firstly, we will apply this formula for first part of this question, i.e; getting a queen out of 52 cards. (please forget club or heart. Because it is given for confusing us. There is no use of it.).

So, Apply formula :

P(E) = n(E)/n(S).
= 1/52.

Now, we will apply this formula in the second part of the question, i.e; getting a king out of 52 cards.

P(E)= n(E)/n(S).
= 1/52.

Now, in the question, the case is given that : getting a queen or a king. Here 'or' means '+' .

Now we will apply '+' sign between these two cases.

The probability of getting a king or a queen is :

= 1/52 + 1/52.
= 2 * 1/52.
= 2/52.
= 1/26.