# Permutation

• May 2nd 2013, 10:56 PM
strangepath
Permutation
Hi I really need help with the following questions. Thanks

1. (a) How many different numbers of 4 digits may be formed with the digits 0,1,2,5,6,7,8 if no digit is used more than once in any number?

(b) How many of the numbers formed in (a) are even?

2. There are 6! Permutations of the 6 letters of the word "square"
(a) In how many of them is "r" the second letter? _ r _ _ _ _
(b) In how many of them are "q" and "e" next to each other?
• May 2nd 2013, 10:58 PM
chiro
Re: Permutation
Hey strangepath.

Try looking into the multivariate hypergeometric distribution for a route to calculating an exact probability (and hence frequency).
• May 2nd 2013, 11:46 PM
ibdutt
Re: Permutation
For the first one i would go like this:
any one of the six numbers ( 1,2,5,6,7,8 ) can assume thta place.
Thus the first place can be filled in = 6 ways
Second place can be filled in = 6 ways , Because second place can be occupied by 0.
Third place can be filled in = 5 ways
and fourth place can be filled in = 4 ways
Thus total number of ways = 6x6x5x4