Probability of Simple Events Return to Table of Contents Slide 7 - - PDF document

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Probability of Simple Events Return to Table of Contents Slide 7 - - PDF document

Slide 1 / 66 Slide 2 / 66 Geometry Probability 2015-10-28 www.njctl.org Slide 3 / 66 Slide 4 / 66 Table of Contents Throughout this unit, the Standards for Mathematical Practice are used. Click on a topic to go to that section MP1:


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Geometry

Probability

2015-10-28 www.njctl.org

Slide 3 / 66 Table of Contents

Probability of Simple Events Probability and Length Probability and Area

Click on a topic to go to that section

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Throughout this unit, the Standards for Mathematical Practice are used. MP1: Making sense of problems & persevere in solving them. MP2: Reason abstractly & quantitatively. MP3: Construct viable arguments and critique the reasoning of

  • thers.

MP4: Model with mathematics. MP5: Use appropriate tools strategically. MP6: Attend to precision. MP7: Look for & make use of structure. MP8: Look for & express regularity in repeated reasoning. Additional questions are included on the slides using the "Math Practice" Pull-tabs (e.g. a blank one is shown to the right on this slide) with a reference to the standards used. If questions already exist on a slide, then the specific MPs that the questions address are listed in the Pull-tab.

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Probability of Simple Events

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  • f Contents

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A sample space is a set of ALL possible outcomes for an activity

  • r experiment.

A sample space is usually denoted using set notation {...} and the possible outcomes are listed as elements in the set {a, b, c, ... z}.

Sample Space

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Find the sample space in the box below each activity. {yellow, blue, red, green} H = heads T = tails {HH, HT, TH, TT} {1, 2, 3, 4, 5, 6} {yellow, green, red}

{(1,1) (1,2) (1,3) (1,4) (1,5) (1,6) (2,1) (2,2) (2,3) (2,4) (2,5) (2,6) (3,1) (3,2) (3,3) (3,4) (3,5) (3,6) (4,1) (4,2)(4,3) (4,4) (4,5)(4,6) (5,1) (5,2)(5,3) (5,4) (5,5)(5,6) (6,1) (6,2) (6,3) (6,4) (6,5) (6,6)}

Sample Space

Click to Reveal Click to Reveal Click to Reveal Click to Reveal Click to Reveal

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If the outcomes in a sample space are equally likely to occur, the theoretical probability of an event P(event) is a numerical value from 0 to 1 that measures the likelihood of an event. You can write the probability of an event as a ratio, decimal or a percent. P(event) = number of favorable outcomes number of possible outcomes · An event with a probability close to 0 is unlikely to occur. · An event with a probability close to 1 is likely to occur. · An event with a probability of 0.5 is just as likely to occur as not.

Impossible Certain Equally Likely to Occur

  • r not Occur

0 less likely 0.5 more likely 1

Theoretical Probability Slide 9 / 66

There are 7 red marbles and 3 green marbles in a bag. One marble is chosen at random. Write the probability that a green marble is chosen. P(Green)

Write as a fraction Write as a decimal Write as a percent

Non - Geometric Examples Slide 10 / 66

P(card) = 1/ 52

Suppose you choose a card from the deck. What is .... P(Heart) = ______ P(3) = ______ P(4 of Spades) = ______

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P(2) = _______ P(even) = _______ P(prime) = _______ P(> 4) = _______

Probability

  • 2. Find the probability of

each event.

  • 1. Find the sample space for the

activity below.

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  • 2. Find the probability of

each event. P(green) = _______ P(orange) = _______

  • 1. Find the sample space for

the activity below.

Probability

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SLIDE 3

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P(heads) = _______ P(tails) = _______

  • 2. Find the probability of

each event.

  • 1. Find the sample space for the

activity below.

Probability Slide 14 / 66

1 A multiple choice question has 14 possible answers,

  • nly one of which is correct. Is it "unlikely" to answer

a question correctly if a random guess is made? Yes No

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2 What is the sample space for flipping a coin twice? A HT, TH B HH, HT, TH, TT C HH, HT, TT D HH, TT, HT, HT

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3 What is the sample space for flipping a coin 3 times? A HHH, TTT, THT, HTH, HHT, TTH, HTH B HHH, HTT, HTH, TTT, HTT, THH, HHT, THT C HTT, THT, HTH, HHH, TTH, TTT D HHH, HHT, HTH, HTT, THH, THT, TTH, TTT

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4 On a multiple choice test, each question has 4 possible

  • answers. If you make a random guess on the first

question, what is the probability that you are correct?

A

4

B

1

C

1/4

D

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5 A die with 12 sides is rolled. What is the probability of rolling a number less than 11? A 1/12 B 10 C 5/6 D 11/12

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6 What is the probability of rolling a number greater than 2 on a number cube? A 1/6 B 1/3 C 1/2 D 2/3

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7 What is the probability of randomly choosing a science book from a shelf that holds 3 mystery books, 5 science books and 4 nature books? A 1/4 B 1/3 C 5/12 D 7/12

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8 A bag contains 6 red marbles, 3 blue marbles, and 7 green marbles. If a marble is randomly selected from the bag, what is the probability that it is blue? A 1/3 B 3/16 C 1/13 D 1/7

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We have evaluated probabilities by counting the number of favorable outcomes and dividing that number by the total number of possible outcomes. In the rest of this unit, you will use a related process in which the division involves geometric measures such as length or

  • area. This process is called geometric probability.

click to reveal

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Probability and Length

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Slide 24 / 66 Using Segments to Find Probability

A B C D Point K on AD is chosen at random. The probability that K is on BC is the ratio of the length of BC to the length of AD. P(K on BC) = BC AD Fill in the blanks. P(K on AC) = P(K on AB) = AD

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2 3 4 5 6 7 8 9 10 11 12 13 14

S Q R T Point H on ST is selected at random. What is the probability that H lies

  • n SR?

Step 1: Find the length of each segment. length of SR = ____________ length of ST = ____________

Using Segments to Find Probability Slide 26 / 66

2 3 4 5 6 7 8 9 10 11 12 13 14

S Q R T Point H on ST is selected at random. What is the probability that H lies

  • n SR?

Step 2: Find the probability. P(H on SR) = _______________ The probability is _______ or _________% .

Using Segments to Find Probability Slide 27 / 66 Using Segments to Find Probability

A B C D E F G H I J K L M 0 1 2 3 4 5 6 7 8 9 10 11 12

JL = __________ A point on AM is chosen at random. Find the probability that the point lies on the given segment.

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A B C D E F G H I J K L M 0 1 2 3 4 5 6 7 8 9 10 11 12

Using Segments to Find Probability

DJ = __________ A point on AM is chosen at random. Find the probability that the point lies on the given segment.

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A B C D E F G H I J K L M 0 1 2 3 4 5 6 7 8 9 10 11 12

Using Segments to Find Probability

BE = __________ A point on AM is chosen at random. Find the probability that the point lies on the given segment.

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A B C D E F G H I J K L M 0 1 2 3 4 5 6 7 8 9 10 11 12

Using Segments to Find Probability

AJ = __________ A point on AM is chosen at random. Find the probability that the point lies on the given segment.

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SLIDE 6

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A B C D E F G H I J K L M 0 1 2 3 4 5 6 7 8 9 10 11 12

Using Segments to Find Probability

A point on AM is chosen at random. Find the probability that the point lies on the given segment. CK = __________

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A B C D E F G H I J K L M 0 1 2 3 4 5 6 7 8 9 10 11 12

Using Segments to Find Probability

A point on AM is chosen at random. Find the probability that the point lies on the given segment. BL = __________

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In the figure at the right = . What is the probability that a point chosen at random on AC will lie on BC? Explain. AB BC 1 2 A B C

Using Segments to Find Probability

If AB = x, then BC = 2x and AC = 3x. BC/AC = 2x/3x = 2/3 Since have a ratio given to us, can we use algebraic expressions to represent this information? Now, can we determine the ratio to represent the probability that a point chosen at random on AC will lie on BC?

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A point between A and B on each number line is chosen at

  • random. What is the probability that the point is between C and D?

A) D) C) B)

0 1 2 3 4 5 6 7 8 A C D B 0 1 2 3 4 5 6 7 8 A C D B 0 1 2 3 4 5 6 7 8 A C D B 0 1 2 3 4 5 6 7 8 A C D B

Using Segments to Find Probability Slide 35 / 66 Real-World Example

A commuter train runs every 25 minutes. If a commuter arrives at the station at a random time, what is the probability that the commuter will have to wait no more than 5 minutes for the train?

Slide 36 / 66 Real-World Example

Which diagram models the situation?

(Each number on the number line represents the number of minutes remaining before the next train leaves.)

0 5 10 15 20 25 D C E 0 5 10 15 20 25 D C E 0 5 10 15 20 25 D C E A) B) C)

Find the probability. P(waiting no more = _______ than 5 minutes)

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A fitness club set up an express exercise circuit. To warm up, a person works out on weight machines for 90 s. Next, the person jogs in place for 60 s, and then takes 30 s to do aerobics. After this, the cycle repeats. If you enter the express exercise circuit at a random time, what is the probability that a friend of yours is jogging in place? What is the probability that your friend will be on the weight machines?

Real-World Example Slide 38 / 66

At the space museum theater, a movie runs for 15 min. There are 5 min between shows. If you enter the theater at a random time, what is the probability that you will have to wait more than 2 min for the next movie to start?

Real-World Example Slide 39 / 66 Real-World Example

A Sunday night sports show is on from 10:00 p.m. to 10:30 p.m. You want to find out if your favorite team won last weekend but forgot that the show had already started. You turn it on at 10:14 p.m. The score is announced at one random time during the show. What is the probability that you haven't missed the repost about your favorite team?

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9 Point X on QT is chosen at random. What is the probability that X is on ST?

A

QT ST

B

ST QT

C

QS ST

D

ST QS

Q R S T

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10 What is the probability that a point chosen at random from EH will be on EF? A 1/3 B 3 C 1/4 D 3/4 3 cm 5 cm 4cm E F G H

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11 If AC = 10, what is the probability that a point chosen at random from AC will land on BC? A 3/5 B 2/5 C 2/3 D 1/2 A B C 6 in

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12 Find the probability that a point chosen at random

  • n AE is on BD.

A 20% B 25% C 30% D 35% E 40%

A B C D E F 0 4 8 12 16 20 24

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13 Point P on AD is chosen at random. For which of the figures below is the probability that P is on BC 25%? Note: Diagrams not drawn to scale. A B C D A B C D 2 5 8 10 A B C D 2 3 4 5 A B C D 1 2 3 4 A B C D 1 2 3 5

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14 You have a 7-cm straw and a 10-cm straw. You want to cut the 10-cm straw into two pieces so that the three pieces make a triangle. If you cut the straw at a random point, what is the probability that you can make a triangle?

A

30%

B

40%

C

60%

D

70%

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Probability and Area

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  • f Contents

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A C

Using Area to Find Probability

Point B in region A is chosen at random. The probability that point B is in region C is the ratio of the area of region C to the ratio of the area of region A. P(B in region C) = area of region C area of region A Find the probability for the given areas. area of region A = 24 in2 area of region C = 3 in2 P(B in region C) = ________

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4 in. A triangle is inscribed in a square. Point N in the square is selected at random. What is the probability that N lies in the shaded region. Step 1: Find the area of each region. area of shaded region = _________ area of square = __________ Step 2: Find the probability. P(N is in shaded region) = _______________ The probability is _______ or _________% .

Using Area to Find Probability

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7 16 4 4 Find the probability that a point chosen at random in the trapezoid with a height of 4 will lie in either of the shaded regions.

Using Area to Find Probability Slide 50 / 66

16 10 A point in the figure to the right is chosen at random. Find the probability to the nearest percent that the point lies in the shaded region.

Using Area to Find Probability Slide 51 / 66

A point in the figure to the right is chosen at random. Find the probability to the nearest percent that the point lies in the shaded region.

7 . 7 m m 10 mm

Using Area to Find Probability Slide 52 / 66

A dart is thrown at random at this dart

  • board. If the dart hits the board, find the

probability to the nearest percent that it will land in the shaded region.

12 ft 6 ft

Using Area to Find Probability Slide 53 / 66

3 c m 50° A point in the figure to the right is chosen at random. Find the probability to the nearest percent that the point lies in the shaded region.

Using Area to Find Probability Slide 54 / 66

Assume that a dart you throw will land on the 1-ft square dartboard and is equally likely to land at any point on the

  • board. Find the probability of hitting each of

the blue, yellow, and red regions. The radii of the concentric circles are 1, 2, and 3 inches,

Using Area to Find Probability - Concentric Circles

P(blue) = P(yellow) = P(red) = 12 in 12 in

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A point in the figure is chosen at

  • random. Find the probability that the

point lies in the shaded region.

3 cm 4 cm 2 cm

Using Area to Find Probability - Concentric Circles Slide 56 / 66

A dart is thrown at random at the dart board to the right. If the dart hits the board, find the probability to the nearest percent that it will land in the shaded region. If dimensions are not given, CHOOSE YOUR OWN A good number to use is, An Even Number

HINT:

Using Area to Find Probability Slide 57 / 66

A dart is thrown at random at the dart board to the right. If the dart hits the board, find the probability to the nearest percent that it will land in the shaded region. This is a square with four semi-circles.

HINT:

Using Area to Find Probability Slide 58 / 66

A dart is thrown at random at the dart board to the right. If the dart hits the board, find the probability to the nearest percent that it will land in the shaded region.

Using Area to Find Probability Slide 59 / 66

In the fundraiser game at the right, players toss darts at a board to try to get them into one of the holes. The diameter

  • f the center hole is 8 in. The diameter
  • f each of the four corner holes is 5 in.

The board is a 20-in.-by-30-in.

  • rectangle. Find the probability that a

tossed dart will go through the indicated hole.

WIN Dart Toss

a) center hole b) any corner c) top right or left d) bottom left

Using Area to Find Probability Slide 60 / 66

15 If a dart hits the target at random, what it the probability that it will land in the shaded region? A 1/3 B 7/16 C 1/9 D 1/4

2 in 6 in

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SLIDE 11

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16 Find the probability that an object falling randomly

  • n the figure will land in the shaded area.

A 0.32 B 0.36 C 0.50 D 0.26

20 in

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17 What is the probability that a randomly dropped marker will fall in the non-shaded region? A 1/16 B 1/4 C 15/16 D 4

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18 Two concentric circles have radii of 11 cm and 17 cm. Find the probability to the nearest thousandth that a point chosen at random from the circles is located

  • utside the smaller circle and inside the larger one.

A 0.021 B 0.097 C 0.581 D 0.647

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19 Find the probability that a point chosen at random in the regular triangle lands in the shaded region. A 25 % B 30 % C 33.3 % D 40 %

3 6

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8 4

20 Find the probability that a point chosen at random lands in the shaded region. Round to the nearest tenth, if necessary. A 39.3 % B 60.7 % C 64 % D 36 %

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21 Find the probability that a point chosen at random in the circle lands in the shaded region. Round to the nearest tenth. A 6.9% B 26.8 % C 50.0% D 55.6% E 27.8%

65° 65°