1
$\begingroup$

I was going through some practice questions in my discrete mathematics book and ran into this one:

Let m, n, k, and l be integers such that m ≥ 1, n ≥ 1, and 1 ≤ l ≤ k ≤ n. After a week of hard work, a student goes to the neighborhood pub. This pub has m different types of beer and n different types of cider on tap. She decides to order k pints: At most one pint of each type, and exactly 'l' pints of cider. Determine the number of ways in which she can order these k pints. The order in which she orders matters.

So far I have: P(m+n, k) as an answer... but I'm sure there's more to it and I have no idea how to start this question. Any help would be greatly appreciated.

  • 0
    Try thinking of it this way: She makes a mental list of which ciders to drink, and then she makes a mental list of which beers to drink, and then she requests the drinks she has decided to have in some order. Counting the number of ways each of these steps can be performed should not be hard, and then you need to combine the numbers appropriately. Good luck! – 2017-01-30

0 Answers 0