5 letters: a, b, c, d, e I randomly pick 3 letters, whats the chance of having a and b in those 3 letters
Probability question on picking letters
0
$\begingroup$
probability
combinatorics
statistics
1 Answers
1
You have a total of $5$ letters and you are choosing $3$ from them. Hence, the total number of ways of choosing three letters is $\dbinom{5}3$.
Number of ways in which you have $a$ and $b$ as two of your three letters is $\dbinom{3}1$, since the third letter you can choose from any of the remaining three letters $c$, $d$ and $e$.
Hence, the probability is _____.
-
0Does the method I describe not mean that I have ordered the choosing of the letters? (I.e one choice for the first letter implies this one must be 'a', for example) I think I meant multiplying by$3!$neglects the order? – 2012-11-25