Expert: Paul Klarreich - 8/22/2011

Question
1. what is the probability of picking a heart and a spade in a standard deck of playing cards?

2. from the same deck of cards, what is the probability of picking either a diamond or a club?

my attempt: qtn 1.
13/52 + 13/52= 26/52

qtn 2;

13/52 x 13/52= 169/2704

Answer
Questioner:bheki
Country:Gauteng, South Africa
Category:Advanced Math
Private:No
Subject:probability

Question:

1. what is the probability of picking a heart and a spade in a standard deck of playing cards?

2. from the same deck of cards, what is the probability of picking either a diamond or a club?

my attempt: qtn 1.
13/52 + 13/52= 26/52

qtn 2;

13/52 x 13/52= 169/2704
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Sorry, these answers don't cut it.
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Picking a heart AND a spade (assuming you pick two cards.):

You want to count:

the two-card subsets that consist of a heart and a spade:  There are 13 * 13 of these.

the two-card subsets:  There are  C(52,2) of these.

Your answer is  13^2/C(52,2), which you can work out.
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Picking a heart OR a spade (assuming you pick one card.):

There are 13+13 such cards, out of 52.

You can finish up.