The answer is C(17,12) * C(5,2).
Explanation:
The 12 jurors from 17 prospective can be chosen in C17,12 ways.
That is: 17! / [12! (17 - 12)! ] = (17*16*15*14*13) / (5*4*3*2*1) = 6188 ways
The 2 alternates are chosen from a group of 17 - 12 = 5. Thas is C5,2
C5,2 = 5! / (2! 3!) = 5*4 / 2 = 10
So, the total number of ways is 6188 * 10 = 61880 ways.
Answer: 61880.