Study Guide for Problem 18

a. Step 1 No replacements 11 People in Total. Only 5 can be in the Group.

Step 2 5C11

Step 3 11*10*9*8*7*6*5*4*3*2*1/ (11-5) 5*4*3*2*1

Step 4  11*10*9*8*7*6*5*4*3*2*1/ (6*5*4*3*2*1)5*4*3*2*1

Step 5 Divide like terms (6*5*4*3*2*1)

Step 6 11*10*9*8*7/5*4*3*2*1

Step 7 55440/120= 462

Answer 462

b. 11 Students in total 2 Must be Jim And Mary 5 makes a Group

Step 2 Since 2 Must be Jim And Mary we make we take it out of the total number of people and the group 11-2 = 9 and 5-2=3

Step 3 3C9

Step 4 9*8*7*6*5*4*3*2*1/(9-3) 3*2*1

Step 5 9*8*7*6*5*4*3*2*1/6*5*4*3*2*1 *3*2*1

Step 6 Divide like Terms 6*5*4*3*2*1

Step 7 9*8*7/ 3*2*1

Step 8    504/6 =84

Answer 84

1 thought on “Study Guide for Problem 18

  1. Your computation steps are very clear – I like the layout! Could you type in the entire problem as it appears in the review sheet (for easy reference by future students), and add some explanation of why you did the steps you did?

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