32nd International Conference on Technology in Collegiate Mathematics
ictcm.com | #ICTCM
ORLANDO, FL
March 12-14
March 12-14 ictcm.com | #ICTCM 32 nd International Conference on - - PowerPoint PPT Presentation
32 nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL March 12-14 ictcm.com | #ICTCM 32 nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14 #ICTCM You Can Count on
32nd International Conference on Technology in Collegiate Mathematics
ictcm.com | #ICTCM
ORLANDO, FL
March 12-14
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM
Associate Professor Broward College Department of Mathematics Davie, Florida sdemsky@broward.edu
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM
A Counting Strategy for Undergraduates
Statistics often have difficulty counting the number of ways in which an event can occur.
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM
A Counting Strategy for Undergraduates
Statistics often have difficulty counting the number of ways in which an event can occur.
– The Fundamental Counting Principle?
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM
A Counting Strategy for Undergraduates
Statistics often have difficulty counting the number of ways in which an event can occur.
– The Fundamental Counting Principle? – Factorials or Permutations?
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM
A Counting Strategy for Undergraduates
Statistics often have difficulty counting the number of ways in which an event can occur.
– The Fundamental Counting Principle? – Factorials or Permutations? – Combinations?
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM
A Counting Strategy for Undergraduates
Statistics often have difficulty counting the number of ways in which an event can occur.
– The Fundamental Counting Principle? – Factorials or Permutations? – Combinations? – More than one of these?
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM
A Counting Strategy for Undergraduates
Statistics often have difficulty counting the number of ways in which an event can occur.
– The Fundamental Counting Principle? – Factorials or Permutations? – Combinations? – More than one of these?
can be used to help students learn how to “count” successfully.
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No
You Can “Count” on Me!
A Counting Strategy for Undergraduates
Department of Mathematics Broward College, Davie, Florida sdemsky@broward.edu
#ICTCM
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No Don has 5 pairs of shoes, 2 pairs of pants, and 3 shirts. If all items match, how many different outfits can he wear?
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No Don has 5 pairs of shoes, 2 pairs of pants, and 3 shirts. If all items match, how many different outfits can he wear?
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No Don has 5 pairs of shoes, 2 pairs of pants, and 3 shirts. If all items match, how many different outfits can he wear?
#ICTCM
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No A multiple-choice test has 6 questions, each with 4 possible
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No A multiple-choice test has 6 questions, each with 4 possible
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No A multiple-choice test has 6 questions, each with 4 possible
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No A multiple-choice test has 6 questions, each with 4 possible
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No A multiple-choice test has 6 questions, each with 4 possible
#ICTCM
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In how many ways can you line up 6 people for a photograph?
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In how many ways can you line up 6 people for a photograph?
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In how many ways can you line up 6 people for a photograph?
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In how many ways can you line up 6 people for a photograph?
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In how many ways can you line up 6 people for a photograph?
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In how many ways can you line up 6 people for a photograph?
#ICTCM
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No To win the top prize in the Florida Fantasy 5 lottery, you must correctly select 5 different numbers from 1-36 (order doesn’t matter). How many selections are possible?
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No To win the top prize in the Florida Fantasy 5 lottery, you must correctly select 5 different numbers from 1-36 (order doesn’t matter). How many selections are possible?
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No To win the top prize in the Florida Fantasy 5 lottery, you must correctly select 5 different numbers from 1-36 (order doesn’t matter). How many selections are possible?
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No To win the top prize in the Florida Fantasy 5 lottery, you must correctly select 5 different numbers from 1-36 (order doesn’t matter). How many selections are possible?
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No To win the top prize in the Florida Fantasy 5 lottery, you must correctly select 5 different numbers from 1-36 (order doesn’t matter). How many selections are possible? 36C5 = 376,992
#ICTCM
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a race with 8 cars, in how many ways can the cars finish 1st place, 2nd place, and 3rd place? Assume no ties.
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a race with 8 cars, in how many ways can the cars finish 1st place, 2nd place, and 3rd place? Assume no ties.
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a race with 8 cars, in how many ways can the cars finish 1st place, 2nd place, and 3rd place? Assume no ties.
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a race with 8 cars, in how many ways can the cars finish 1st place, 2nd place, and 3rd place? Assume no ties.
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a race with 8 cars, in how many ways can the cars finish 1st place, 2nd place, and 3rd place? Assume no ties.
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a race with 8 cars, in how many ways can the cars finish 1st place, 2nd place, and 3rd place? Assume no ties.
8P3 = 336
#ICTCM
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a certain state, license plates are 3 letters followed by 3 numbers with no repetitions in either
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a certain state, license plates are 3 letters followed by 3 numbers with no repetitions in either
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a certain state, license plates are 3 letters followed by 3 numbers with no repetitions in either
# ways to arrange 3 different letters # ways to arrange 3 different numbers
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a certain state, license plates are 3 letters followed by 3 numbers with no repetitions in either
# ways to arrange 3 different letters # ways to arrange 3 different numbers
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a certain state, license plates are 3 letters followed by 3 numbers with no repetitions in either
# ways to arrange 3 different letters # ways to arrange 3 different numbers
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a certain state, license plates are 3 letters followed by 3 numbers with no repetitions in either
# ways to arrange 3 different letters # ways to arrange 3 different numbers
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a certain state, license plates are 3 letters followed by 3 numbers with no repetitions in either
# ways to arrange 3 different letters # ways to arrange 3 different numbers
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a certain state, license plates are 3 letters followed by 3 numbers with no repetitions in either
# ways to arrange 3 different letters # ways to arrange 3 different numbers
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a certain state, license plates are 3 letters followed by 3 numbers with no repetitions in either
26 26P3
# ways to arrange 3 different numbers
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a certain state, license plates are 3 letters followed by 3 numbers with no repetitions in either
26 26P3
# ways to arrange 3 different numbers
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a certain state, license plates are 3 letters followed by 3 numbers with no repetitions in either
26 26P3
# ways to arrange 3 different numbers
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a certain state, license plates are 3 letters followed by 3 numbers with no repetitions in either
26 26P3
# ways to arrange 3 different numbers
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a certain state, license plates are 3 letters followed by 3 numbers with no repetitions in either
26 26P3
# ways to arrange 3 different numbers
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a certain state, license plates are 3 letters followed by 3 numbers with no repetitions in either
26 26P3
# ways to arrange 3 different numbers
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a certain state, license plates are 3 letters followed by 3 numbers with no repetitions in either
26 26P3 10 10P3
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No In a certain state, license plates are 3 letters followed by 3 numbers with no repetitions in either
32nd International Conference on Technology in Collegiate Mathematics ORLANDO, FL | MARCH 12-14
#ICTCM Are the objects you’re counting all the same type?
Use Fundamental Counting Principle
Are you putting the objects in
No
Are you arranging ALL the objects?
Use Combinations: nCr
No Yes
Use Factorial: n! Use Permutations: nPr
Yes No
w ways x ways y ways z ways
= w·x·y·z ways
Can you repeat a selection?
Yes Yes No
You Can “Count” on Me!
A Counting Strategy for Undergraduates
Department of Mathematics Broward College, Davie, Florida sdemsky@broward.edu