EOCT Practice A spinner has 3 sections, each with different point values and areas. - The 1-point section is 2/3 of the area of the spinner. - The 2-point section is1/4 of the area of the spinner. - The 3-point section is 1/12 of the area of the spinner. To the nearest tenth of a point, what is the expected value? a)0.7 b)1.4 c)2.0 d)6.0 b

EOCT Practice Greg wrote the numbers 1 through 9 on pieces of paper and placed them in a hat. He will randomly select one piece of paper from the hat. He will not replace it. Greg will then randomly select a second piece of paper from the hat. What is the probability that Greg will select a piece of paper with an odd number on it and then, select one with an even number on it? a)20/81 b)5/18 c)9/17 d)19/18 b

Vocabulary Population : is a group of people or objects that you want information about Sample : is a subset of the population being studied

Types of samples Self-selected sample : members of a population can volunteer to be in the sample

Self-selected sample Examples: Filling out a survey because you want to. Calling an 800 number on your receipt to fill out a survey about your experience in the store while you shopped.

Types of samples Systematic sample : a RULE is used to select members of a population

Systematic sample Example: Selecting every 10 th person

Types of samples Convenience sample : easy to reach members of a population are selected

Convenience sample Example: Asking the first 10 people that walk through the front door.

Types of samples Random sample : each member of a population has an equal chance of being selected

Random sample Example: Using a random number generator to select someone out of the population

Unbiased vs Biased

Unbiased Unbiased sample : is representative of the population you want information about.

Biased Biased sample : a sample that over represents the population or under represents PART of the population

Unbiased vs Biased Example: You polling people at a pet store if they are in favor of a local dog park in the area. Is this biased or unbiased? biased

John surveys every fifth person leaving a pet supply store. Of those surveyed, ¾ support the city manager’s proposition to tear down the old library and replace the area with the construction of a new pet park. John plans to write a letter to the editor of the local newspaper about the proposal for the new pet park stating that there is tremendous support from the citizens of the town for constructing a new pet park. a) Can the conclusion John stated be accurately supported? b) Suggest another plan for obtaining a good sample population. Sampling No Example: survey at multiple locations in the town

I want to know the average height of students at Hillgrove High School. What would be a good method to find this number without checking every student? Sampling Example: Having a list of every student and choosing every 10th

Your school is conducting a survey on a proposed dress code. The first 20 students entering the school in the morning are surveyed. What type of sampling method is used? a) Convenience b) Random c) Stratified random d) Systematic Sampling A. Convenience

A principal is surveying the parents of his school to find out if they support extending the school day by 20 minutes. Which of the following methods of choosing a sample will most likely result in a sample that is representative of all parents? a) Surveying all the parents at a parent – teacher meeting b) Surveying 50 parents of 9 th grade students c) Surveying all the parents who volunteer for a school fundraiser d) Selecting every 20 th name from an alphabetical list of all parents and surveying those parents. Sampling D.

Which of the following questions is not potentially biased? a) Do you prefer creamy macaroni and cheese or bland rice? b) Don’t you feel the city is wasting money by building that new stadium? c) Do you prefer shopping online or in the stores? d)Don’t you agree that the driving age should be raised to 18 to decrease the number of accidents? Sampling C.