There are 42 citizens called for jury duty. Eleven are randomly chosen to for the interview phase. How many different ways can the group of interviewees be made?

The quick way to get the answer is just type "42 choose 11" into Google.

Or if you want to figure it out yourself, you have 42 choices for the first potential juror, 41 choices for the second potential juror, etc.

Now before you stop there, you only care about the combination of the 11 people chosen, not what order they are selected, so you need to divide by the ways to arrange 11 people.

Final expression:

C (42,11) = (42 * 41 * 40 * 39 * 38 * 37 * 36 * 35 * 34 * 33 * 32) / (11 * 10 * 9 * 8 * 7 * 6 * 5 * 4 * 3 * 2 * 1)

Answers:

4,280,561,376 ways

42,11