# N YS CO MMO N COR E MAT N YS CO MMO N COR E MAT H E MAT I C S C U RR I C U LU M Probability and Sampling Grade 7 Module 5 2012 Common Core, Inc. All rights reserved. commoncore.org A Story of Ratios N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M A Story of Ratios Session Objectives 1. Discuss the key ideas of what students learn in the module Statistics and Probability. 2. Examine sample problems to learn how students progress through the Common Core Standards in Statistics and Probability. 3. Questions?

2012 Common Core, Inc. All rights reserved. commoncore.org A Story of Ratios N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M Statistics and Probability Module Has 5 lessons Covers Standards Topic A 7.SP.C.6 Calculating and Interpreting

7.SP.C.7 7.SP.C.8c Probabilities Has 7 lessons Covers Standards Topic B 7.SP.C.5 7.SP.C.6 Estimating Probabilities 7.SP.C.7 7.SP.C.8a-b Mid-Module Assessment

Has 3 lessons Topic C Covers Random Standards Sampling and Estimated 7.SP.B.3 7.SP.B.4 Population Characteristics Has 8 lessons Topic D Covers Standards Comparing Populations

Comparing Populations 7.SP.A.1 7.SP.A.2 End-of-Module Assessment 2012 Common Core, Inc. All rights reserved. commoncore.org A Story of Ratios N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M Statistics and Probability Module Topic A Calculating and Interpreting Probabilities Topic C Random Sampling and Estimated Population Characteristics 2012 Common Core, Inc. All rights reserved. commoncore.org

Topic B Estimating Probabilities Topic D Comparing Populations N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M A Story of Ratios The Terminology of Probability Jamal, a 7th grader, wants to design a game that involves tossing paper cups. Jamal tosses a paper cup five times and records the outcome of each toss. An outcome is the result of a single trial of an experiment. Here are the results of each toss: Jamal noted that the paper cup could land in one of three ways: on its side, right side up, or upside down. The collection of these three outcomes is called the sample space of the experiment. The sample space of an experiment is the set of all possible outcomes of that experiment. Lesson 3 Example 1

2012 Common Core, Inc. All rights reserved. commoncore.org N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M A Story of Ratios Equally Likely Outcomes? The sample space for the paper cup toss was on its side, right side up, and upside down. Do you think each of these outcomes has the same chance of occurring? If they do, then they are equally likely to occur. The outcomes of an experiment are equally likely to occur when the probability of each outcome is equal. You and your partner toss the paper cup 30 times and record in a table the results of each toss. Lesson 3 Example 2 2012 Common Core, Inc. All rights reserved. commoncore.org N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M

approximately 120 tosses. If time permits, allow students to carry out the experiment for a total of 120 tosses, or combine results of students to examine the number of outcomes for approximately 120 tosses. Compare the predicted numbers and the actual numbers. 2012 Common Core, Inc. All rights reserved. commoncore.org A Story of Ratios N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M Calculating Probabilities of Compound Events If the researchers conducting the experiment add food in the simple maze such that the probability of each mouse turning left is now 0.7, what is the such that the probability of each mouse turning left is now 0.7, what is the probability that only one of the three mice will turn probability that only one of the three mice will turn left? left? L LLL

0.7(0.7)(0.7) = 0.343 R LLR 0.7(0.7)(0.3) = 0.147 L LRL 0.7(0.3)(0.7) = 0.147 R LRR 0.7(0.3)(0.3) = 0.063 L

L R The probability that only one of the three mice will turn left is RLL L 0.3(0.7)(0.7) = 0.147 0.063 + 0.63 + 0.63 = 0.189. L R R L RLR 0.3(0.7)(0.3) = 0.063 RRL

0.3(0.3)(0.7) = 0.063 RRR 0.3(0.3)(0.3) = 0.027 R R Lesson 7 Exit Ticket Question 3 2012 Common Core, Inc. All rights reserved. commoncore.org N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M Statistics and Probability Module 2012 Common Core, Inc. All rights reserved. commoncore.org A Story of Ratios N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M

A Story of Ratios Using Simulation to Estimate a Probability 1. Using colored disks, describe how one at-bat could be simulated for a baseball player who has a batting average of 0.300. Note that a batting average of 0.300 means the player gets a hit (on average) three times out of every ten times at bat. Be sure to state clearly what a color represents. Lesson 11 Exercise 1 2012 Common Core, Inc. All rights reserved. commoncore.org N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M A Story of Ratios Using Simulation to Estimate a Probability 2. Using colored disks, describe how one at-bat could be simulated for a player who has a batting average of 0.273. Note that a batting average of 0.273 means that on average,

the player gets 273 hits out of 1000 at-bats. 25256 65205 72597partner 00562 why 12683it 90674 Discuss with your is NOT78923 a good96568 ideas32177 to use33855 colored disks to simulate this situation. 76635 92290 88864 72794 14333 79019 05943 77510 74051 87238 Use 000 272 to represent a hit 07895 86481 94036 12749 24005 80718 13144 66934 54730 77140 273 999 represents a miss Lesson 11 Exercise 2 2012 Common Core, Inc. All rights reserved. commoncore.org

A Story of Ratios N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M Using Simulation to Estimate a Probability 3. Continuing on the first line of the random numbers above, what would the hit/non-hit outcomes be for the next six atbats? Be sure to state the random number and whether it simulates a hit or non-hit. 25256 65205 72597 00562 12683 90674 78923 96568 32177 33855 76635 92290 88864 72794 14333 79019 05943 77510 74051 87238 07895 86481 94036 12749 24005 80718 13144 66934 54730 77140 H M M M M Lesson 11 Exercise 3

2012 Common Core, Inc. All rights reserved. commoncore.org H M N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M A Story of Ratios Using Simulation to Estimate a Probability 3. Suppose that a type A blood donor is needed for a certain surgery. Carry out a simulation to answer the following question: If 40% of donors have type A blood, what is an estimate of the probability that it will take at least four donors to find one with type A blood? Lesson 11 Practice Set Exercise 3 2012 Common Core, Inc. All rights reserved. commoncore.org

N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M A Story of Ratios Mid-Module Assessment In the game of Darts, players throw darts at a circle divided into 20 wedges. In one variation of the game, the score for a throw is equal to the wedge number that the dart hits. So, if the dart hits anywhere in the 20 wedge, you earn 20 points for that throw. a. If you are equally likely to land in any wedge, what is the probability you will score 20 points? Exercise 3 2012 Common Core, Inc. All rights reserved. commoncore.org N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M A Story of Ratios Mid-Module Assessment In the game of Darts, players throw darts at a circle divided into

20 wedges. In one variation of the game, the score for a throw is equal to the wedge number that the dart hits. So, if the dart hits anywhere in the 20 wedge, you earn 20 points for that throw. b. If you are equally likely to land in any wedge, what is the probability you will land in the upper right and score 20, 1, 18, 4, 13, or 6 points? 2012 Common Core, Inc. All rights reserved. commoncore.org N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M A Story of Ratios Mid-Module Assessment In the game of Darts, players throw darts at a circle divided into 20 wedges. In one variation of the game, the score for a throw is equal to the wedge number that the dart hits. So, if the dart hits anywhere in the 20 wedge, you earn 20 points for that throw. c. Below are the results of 100 throws for one player. Does this player appear to have a tendency to land in the upper right more often than we would expect if the player was equally likely to land in any wedge?

2012 Common Core, Inc. All rights reserved. commoncore.org N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M Statistics and Probability Module 2012 Common Core, Inc. All rights reserved. commoncore.org A Story of Ratios N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M A Story of Ratios What is Random? Write down a sequence of heads/tails you think would typically occur if you tossed a coin 20 times. Compare your sequence to the ones written by some of your classmates. How are they alike? How are they different? Lesson 14 Exercise 1

Selecting a Sample Look at the poem, Casey at the Bat by Ernest Thayer, and select eight words you think are representative of words in the poem. Record the number of letters in each word you selected. Find the mean number of letters in the words you chose. Lesson 14 Exercise 4 2012 Common Core, Inc. All rights reserved. commoncore.org N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M A Story of Ratios Selecting a Sample Working with a partner, follow your teachers instruction for randomly choosing eight words. Begin with the title of the poem and count a hyphenated word as one word. a. Record the eight words you randomly selected and find the mean number of letters in those words. b. Compare the mean of your random sample to the mean you

found in Exercise 4. Explain how you found the mean for each sample. Lesson 14 Exercise 6 2012 Common Core, Inc. All rights reserved. commoncore.org N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M A Story of Ratios Selecting a Sample As a class, compare the means from Exercise 4 and the means from Exercise 6. Your teacher will provide a back-to-back stem and leaf plot to compare the means. Record your mean from Exercise 4 and your mean for Exercise 6 on this plot. Do you think means from Exercise 4 or the means from Exercise 6 The actual mean of the words in the poem Casey at are more representative of the mean of all of the words in the the Batyour is 4.2 letters. poem? Explain

choice. Lesson 14 Exercise 7- 9 2012 Common Core, Inc. All rights reserved. commoncore.org N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M A Story of Ratios Sampling Variability The owners of a gym have been keeping track of how long each person spends at the gym. Eight hundred of these times (in Suppose you were to take another random sample from the same minutes) are shown in the population tables located at the end of population of times at the gym. Could the new sample mean be closer to the lesson. From this population you will take a random sample. Do you think that the mean of these five observations is the population mean than the mean of these five observations? Further? Could the population mean be greater than the number

exactly correct for the population mean? you calculated? Smaller? in your sample? What are the five observations For the sample that you selected, calculate the sample mean. Lesson 17 Exercises 1 - 4 2012 Common Core, Inc. All rights reserved. commoncore.org A Story of Ratios N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M Sampling Variability Use all the sample means to make a dot plot using the axis given below. (Remember, if you have repeated or close values, stack Suppose a statistician

to take a random sample of size 5 from the population of the dots onethat above theplans other.) What do you see in the dot plot that demonstrates sampling times spent at the gym and that he or she will use the sample mean as an estimate of the variability? population mean. Approximately how far can the statistician expect the sample mean to be from the population mean? Lesson 17 Exercises 8-11 2012 Common Core, Inc. All rights reserved. commoncore.org N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M Statistics and Probability Module 2012 Common Core, Inc. All rights reserved. commoncore.org

A Story of Ratios A Story of Ratios N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M Why Worry about Sampling Variability? There are three bags, Bag , Bag , and Bag , with 100 numbers , Bag , and Bag , with 100 numbers , and Bag , with 100 numbers , with 100 numbers in each bag. You and your classmates will investigate the population mean (the mean of all 100 numbers) in each bag. Each set of numbers has the same range. However, the population means of each set may or may not be the same. We will see who can uncover the mystery of the bags! A Lesson 21 2012 Common Core, Inc. All rights reserved. commoncore.org B C

A Story of Ratios N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M Why Worry about Sampling Variability? To begin your investigation, start by selecting a random sample of ten numbers from Bag , Bag , and Bag , with 100 numbers . Remember to mix the numbers in the bag first. Then, select one number from the bag. Do not put it back into the bag. Write the number in the chart below. Continue selecting one number at a time until you have selected ten numbers. Mix up b. Do you think the mean of all the numbers in Bag , Bag , and Bag , with 100 numbers might be the numbers in the bag between each selection. 10? Why or why not? c. Based on the dot plot, what would you estimate the mean of a. Create a dotinplot your sample the numbers

Bag , Bag , and Bag , with 100 numbers of to be? How did you make of yourten numbers. Use a dot to represent each number estimate? in the sample. Lesson 21 Exercise 1 2012 Common Core, Inc. All rights reserved. commoncore.org A N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M A Story of Ratios Why Worry about Sampling Variability? Repeat the process by selecting a random sample of ten numbers from Bag , and Bag , with 100 numbers . b. Based on your dot plot, do you think the mean of the numbers in Bag , and Bag , with 100 numbers is the same or different than the mean of the numbers in Bag , Bag , and Bag , with 100 numbers ? Explain

thinking. a. Create a dot plot of your sample of tenyournumbers. Use a dot to represent each number in the sample. Lesson 21 Exercise 2 2012 Common Core, Inc. All rights reserved. commoncore.org B N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M A Story of Ratios Why Worry about Sampling Variability? Repeat the process by selecting a random sample of ten numbers from Bag C. b. Based on your dot plot, do you think the mean of the numbers in Bag , with 100 numbers is the same or different than the mean of the numbers in Bag , Bag , and Bag , with 100 numbers ? Explain thinking. a. Create a dot plot of your sample of tenyournumbers.

Use a dot to represent each number in the sample. Lesson 21 Exercise 3 2012 Common Core, Inc. All rights reserved. commoncore.org C A Story of Ratios N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M Why Worry about Sampling Variability? Calculate the mean of the numbers for each of the samples from Bag , Bag , and Bag , with 100 numbers , Bag, , and Bag , with 100 numbers , and Bag , with 100 numbers . c. Calculate the difference of sample mean for Bag , Bag , and Bag , with 100 numbers minus sample mean for Bag B (, Bag , and Bag , with 100 numbers , and Bag , with 100 numbers ). Based on this difference, can you be sure which bag has the larger population mean? Why or why not?

Lesson 21 Exercise 5 2012 Common Core, Inc. All rights reserved. commoncore.org A B C A Story of Ratios N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M Why Worry about Sampling Variability? Have each student plot his or her sample mean for the sample from Bag , Bag , and Bag , with 100 numbers ononatheclass dot labeled ofmean

samples fromin Bag Bag Based class dot plotsplot, of the sample means,Means do you think the of the numbers , Bag , and Bag , with 100 numbers , Bag , and Bag , with 100 numbers . Then, for the means , and Bag , with 100 numbers and , with 100 numbers . and construct the mean of the class numbersdot in Bagplots , and Bag , with 100 numbers are different? Do you

think thefrom mean ofBags the numbers in Bag , Bag , and Bag , with 100 numbers and the mean of the numbers in Bag , with 100 numbers are different? Explain your answers. A Lesson 21 Exercise 6 2012 Common Core, Inc. All rights reserved. commoncore.org B C A Story of Ratios N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M Why Worry about Sampling Variability? Plot your difference of the means, (, Bag , and Bag , with 100 numbers , and Bag , with 100 numbers ), on a class dot plot.

Describe the distribution of differences plotted on the graph. Remember to discuss center and spread. Lesson 21 Exercise 10 2012 Common Core, Inc. All rights reserved. commoncore.org A B A Story of Ratios N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M Why Worry about Sampling Variability? Calculate the sample mean of Bag , Bag , and Bag , with 100 numbers minus the sample mean of Bag , with 100 numbers , (, Bag , and Bag , with 100 numbers , with 100 numbers ). Plot your difference (, Bag , and Bag , with 100 numbers , with 100 numbers ) on a class dot plot. How do the centers of the class dot plots for (, Bag , and Bag , with 100 numbers , and Bag , with 100 numbers ) and (, Bag , and Bag , with 100 numbers , with 100 numbers ) compare?

Lesson 21 Exercises 14-16 2012 Common Core, Inc. All rights reserved. commoncore.org A C A Story of Ratios N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M Why Worry about Sampling Variability? Each bag has a population mean that is either 10.5 or 14.5. State what you think the population mean is for each bag. Explain your choice for each bag. 14.5 A Lesson 21 Exercise 17 2012 Common Core, Inc. All rights reserved. commoncore.org

14.5 B 10.5 C N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M A Story of Ratios End-of-Module Assessment Students in a random sample of 57 students were asked to measure their hand-spans (distance from outside of thumb to outside of little finger when the hand is stretched out as far as possible). The graphs below show the results for the males and females. Exercise 2 2012 Common Core, Inc. All rights reserved. commoncore.org

N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M A Story of Ratios End-of-Module Assessment a. Based on these data, do you think there is a difference between the population mean hand-span for males and the population mean hand-span for females? Justify your answer. Exercise 2 2012 Common Core, Inc. All rights reserved. commoncore.org N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M A Story of Ratios End-of-Module Assessment b. The same students were asked to measure their heights, with the results shown below.

Are these height data more or less convincing of a difference in the population mean height than the hand span data are of a difference in population mean handspan? Explain. Exercise 2 2012 Common Core, Inc. All rights reserved. commoncore.org N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M Questions? 2012 Common Core, Inc. All rights reserved. commoncore.org A Story of Ratios N YS C O M M O N C O R E M AT H E M AT I C S C U R R I C U L U M A Story of Ratios Key Points Probabilities can be estimated using simulation.

The results of random samples are representative of a population. It is important to consider sampling variability when comparing two populations. 2012 Common Core, Inc. All rights reserved. commoncore.org