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13.5 Counting Principles

Addition and Multiplication Principles, permutations of distinct and repeated objects, combinations, and counting subsets of a set.

Algebra and Trigonometry 2e, 13.5 Counting Principles

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43 exercises

Solve counting problems using the addition principle.

ⓐ Seven red and five green marbles are placed in a bag. How many marbles are there to choose from?

ⓑ Let the set A = {−5,−3,−1,2,3,4,5,6}. How many ways are there to choose a negative or an even number from A?

ⓒ A student is shopping for a new computer. He is deciding among 2 desktop computers and 3 laptop computers. What is the total number of computer options?

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13.5 Exercise 5

Solve counting problems using the multiplication principle.

  1. ⓐ Diane packed 2 skirts, 3 blouses, and 2 sweaters for her business trip. She will need to choose a skirt and a blouse for each outfit and decide whether to wear the sweater. Use the Multiplication Principle to find the total number of possible outfits.
  2. ⓑ A restaurant offers a lunch special that includes an entree, a main dish, and a b…
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13.5 Exercise 11

A student is shopping for a new computer. He is deciding among 3 desktop computers and 4 laptop computers. What is the total number of computer options?

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13.5 Exercise 13

A restaurant offers a breakfast special that includes a breakfast sandwich, a side dish, and a beverage. There are 3 types of breakfast sandwiches, 4 side dish options, and 5 beverage choices. Find the total number of possible breakfast specials.

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13.5 Exercise 15

How many ways can the family line up for the portrait?

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13.5 Exercise 16

How many ways can the photographer line up 3 family members?

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13.5 Exercise 17

How many ways can the family line up for the portrait if the parents are required to stand on each end?

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Finding the Number of Permutations Using the Formula

A professor is creating an exam of 9 questions from a test bank of 12 questions. How many ways can she select and arrange the questions?

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13.5 Exercise 19

How many ways can the 7 actors line up?

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13.5 Exercise 20

How many ways can 5 of the 7 actors be chosen to line up?

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Finding the Number of Combinations Using the Formula

A fast food restaurant offers five side dish options. Your meal comes with two side dishes.

  1. ⓐHow many ways can you select your side dishes?
  2. ⓑHow many ways can you select 3 side dishes?
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13.5 Exercise 22

An ice cream shop offers 10 flavors of ice cream. How many ways are there to choose 3 flavors for a banana split?

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Finding the Number of Subsets of a Set

A restaurant offers butter, cheese, chives, and sour cream as toppings for a baked potato. How many different ways are there to order a potato?

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13.5 Exercise 24

A sundae bar at a wedding has 6 toppings to choose from. Any number of toppings can be chosen. How many different sundaes are possible?

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Finding the Number of Permutations of n Non-Distinct Objects

Find the number of rearrangements of the letters in the word DISTINCT.

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13.5 Exercise 26

Find the number of rearrangements of the letters in the word CARRIER.

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13.5 Exercise 27

Assume that there are n n ways an event A A can happen, m m ways an event B B can happen, and that Aand B A \text{and}\textrm{ } B are non-overlapping.

Use the Addition Principle of counting to explain how many ways event Aor B A \text{or}\textrm{ } B can occur.

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13.5 Exercise 29

Answer the following questions.

When given two separate events, how do we know whether to apply the Addition Principle or the Multiplication Principle when calculating possible outcomes? What conjunctions may help to determine which operations to use?

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13.5 Exercise 31

Answer the following questions.

What is the term for the arrangement that selects r r objects from a set of n n objects when the order of the r r objects is not important? What is the formula for calculating the number of possible outcomes for this type of arrangement?

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13.5 Exercise 33

Determine whether to use the Addition Principle or the Multiplication Principle. Then perform the calculations.

Let the set B={−23,−16,−7,−2,20,36,48,72}. B = \left\{- 23 , - 16 , - 7 , - 2 , 20 , 36 , 48 , 72\right\} . How many ways are there to choose a positive or an odd number from A? A ?

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13.5 Exercise 35

Determine whether to use the Addition Principle or the Multiplication Principle. Then perform the calculations.

How many ways are there to pick a paint color from 5 shades of green, 4 shades of blue, or 7 shades of yellow?

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13.5 Exercise 37

Determine whether to use the Addition Principle or the Multiplication Principle. Then perform the calculations.

How many outcomes are possible from tossing a coin and rolling a 6-sided die?

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13.5 Exercise 39

Determine whether to use the Addition Principle or the Multiplication Principle. Then perform the calculations.

How many ways are there to construct a string of 3 digits if numbers can be repeated?

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13.5 Exercise 41

Compute the value of the expression.

P(5,2) P \left(5 , 2\right)

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13.5 Exercise 43

Compute the value of the expression.

P(3,3) P \left(3 , 3\right)

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13.5 Exercise 45

Compute the value of the expression.

P(11,5) P \left(11 , 5\right)

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13.5 Exercise 47

Compute the value of the expression.

C(12,4) C \left(12 , 4\right)

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13.5 Exercise 49

Compute the value of the expression.

C(7,6) C \left(7 , 6\right)

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13.5 Exercise 51

Find the number of subsets in each given set.

{1,2,3,4,5,6,7,8,9,10} \left\{1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10\right\}

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13.5 Exercise 53

Find the number of subsets in each given set.

A set containing 5 distinct numbers, 4 distinct letters, and 3 distinct symbols

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13.5 Exercise 55

Find the number of subsets in each given set.

The set of two-digit numbers between 1 and 100 containing the digit 0

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13.5 Exercise 57

Find the distinct number of arrangements.

The letters in the word “academia”

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13.5 Exercise 59

Find the distinct number of arrangements.

The symbols in the string #,#,#,@,@,$,$,$,%,%,%,%

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13.5 Exercise 61

The set, S S consists of 900,000,000 \text{900},\text{000},\text{000} whole numbers, each being the same number of digits long. How many digits long is a number from S? S ? (Hint: use the fact that a whole number cannot start with the digit 0.)

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13.5 Exercise 63

Can C(n,r) C \left(n , r\right) ever equal P(n,r)? P \left(n , r\right) ? Explain.

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13.5 Exercise 65

How many arrangements can be made from the letters of the word “mountains” if all the vowels must form a string?

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13.5 Exercise 67

A cell phone company offers 6 different voice packages and 8 different data packages. Of those, 3 packages include both voice and data. How many ways are there to choose either voice or data, but not both?

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13.5 Exercise 69

A wholesale T-shirt company offers sizes small, medium, large, and extra-large in organic or non-organic cotton and colors white, black, gray, blue, and red. How many different T-shirts are there to choose from?

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13.5 Exercise 71

An art store has 4 brands of paint pens in 12 different colors and 3 types of ink. How many paint pens are there to choose from?

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13.5 Exercise 73

How many ways can a baseball coach arrange the order of 9 batters if there are 15 players on the team?

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13.5 Exercise 75

A motorcycle shop has 10 choppers, 6 bobbers, and 5 café racers—different types of vintage motorcycles. How many ways can the shop choose 3 choppers, 5 bobbers, and 2 café racers for a weekend showcase?

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13.5 Exercise 77

Just-For-Kicks Sneaker Company offers an online customizing service. How many ways are there to design a custom pair of Just-For-Kicks sneakers if a customer can choose from a basic shoe up to 11 customizable options?

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13.5 Exercise 79

Suni bought 20 plants to arrange along the border of her garden. How many distinct arrangements can she make if the plants are comprised of 6 tulips, 6 roses, and 8 daisies?

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Adapted from College Algebra © 2021 Rice University. Licensed under CC BY 4.0. Sources: College Algebra 2e, Algebra and Trigonometry 2e, Precalculus 2e, College Algebra with Corequisite Support 2e. Imported at revision 4922e46.