Do Now 1. Find the number of permutations with 7 books taken 4 at a time. 2. Find the number of permutations of the letters in each word: TennesseeGeorgiaAlabama
Pg ; 9-50 all 9. 4, , , , ,243, , , ,160
Continued… , , , ,814, ,459, ,366, ,909, ,252, ,518, , , , , ,107,
Continued…again…
Combinations
Essential Question: How do I solve problems involving combinations?
Formula:
Things you need to know: In a permutation, ORDER matters. In a combination, order does NOT matter. The value of combinations will be less than most permutations. You will use the nCr function in the calculator.
Problem Types: Determine the values for “n” (total number of objects) and “r” (the rate the objects are taken). “n” is always larger. Multiply the combinations together using the nCr key if there is more than one type of object. Find the probability of an event by dividing the product of individual combinations by the total number of combinations. Your answer is a %.
Example 1 Find the # of ways to purchase 3 different kinds of juice from a selection of 10 different juices. (The order in which they are chosen doesn’t matter, making this a combination). 10 C 3 = 120
Example 2 The difference between a permutation and a combination: COMBO: How many ways are there to choose a committee of 3 people from a group of 5? 5 C 3 = 10 Permutation: How many ways are there to choose 3 separate office holders (chairman, secretary, and treasurer) from a group of 5? 5 P 3 = 60
Example 3 How many different ways are there to purchase 2 CD’s, 3 cassettes, and 1 videotape from 7 CD titles, 5 cassette titles, and 3 videotape titles? 7 C 2 5 C 3 3 C 1 = 630
Example 4 In a recent survey of 25 voters, 17 favor a new city regulation and 8 oppose it. Find the probability that in a random sample of 6 respondents from this survey, exactly 2 favor the proposal regulation, and 4 oppose it = 5.4%
Assignment: Pg. 647, #’s 4-39a.
Pg. 647, 4-39a / % ,792,840
Continued… , % % % % 34. Combo 35. Combo 36. Permutation 37. Permutation 38. Permutation 39. 2,598,960