# Splash Screen Example 7-4b Objective Predict the actions of a larger group by using a sample.

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Splash Screen

Example 7-4b Objective Predict the actions of a larger group by using a sample

Example 7-4b Vocabulary Sample A randomly selected group chosen for the purpose of collecting data

Example 7-4b Vocabulary Population The entire group of items or individuals from which the samples under consideration are taken

Example 7-4b Vocabulary Unbiased sample A sample that is selected so that it is representative of the entire population

Example 7-4b Vocabulary Simple random sample A sample where each item or person in the population is as likely to be chosen as any other

Example 7-4b Vocabulary Stratified random sample A sampling method in which the population is divided into similar, non-overlapping groups

Example 7-4b Vocabulary Systematic random sample A sampling method in which the items or people are selected according to a specific time or item interval

Example 7-4b Vocabulary Biased sample A sample drawn in such a way that one or more parts of the population are favored over others

Example 7-4b Vocabulary Convenience sample A sample which includes members of the population that are easily accessed

Example 7-4b Vocabulary Voluntary response sample A sample which involves only those who want to participate in the sampling

Lesson 7 Contents Example 1Describe Samples Example 2Describe Samples Example 3Using Sampling to Predict Example 4Using Sampling to Predict

Example 7-1a To determine which school lunches students like most, every twentieth student to walk into the cafeteria is surveyed. Describe the sample. Answer: Random, unbiased Every 20 th student is surveyed 1/4 Random sample Population is those entering cafeteria Unbiased

Example 7-1b To determine which CDs customers like most, every tenth customer to walk into the music store is surveyed. Describe the sample. Answer: Unbiased, random 1/4

Example 7-2a To determine what sports teenagers like, the student athletes on the girls’ field hockey team are surveyed. Describe the sample. Answer: Biased, Convenience Girl’s on field hockey team are more likely to choose hockey as favorite sport 2/4 Biased Only the hockey team is survey Convenience

Example 7-2b To determine what restaurant teenagers like, the teenagers eating at Pete’s Diner are surveyed. Describe the sample. Answer: Biased, Convenience 2/4

Example 7-3a BOOKS The student council is trying to decide what types of books to sell at its annual book fair to help raise money for the eighth-grade trip. It surveys 40 students at random. The books they prefer are in the table. What percent of the students prefer mysteries? 8short stories 11sports 9adventure novel 12mystery Number of Students Book Type Write proportion to find percent 3/4

Example 7-3a BOOKS The student council is trying to decide what types of books to sell at its annual book fair to help raise money for the eighth-grade trip. It surveys 40 students at random. The books they prefer are in the table. What percent of the students prefer mysteries? Remember: Percent has a denominator of 100 x z 100 3/4 Define the variable The second ratio is based on preference of mystery books to total books

Example 7-3a BOOKS The student council is trying to decide what types of books to sell at its annual book fair to help raise money for the eighth-grade trip. It surveys 40 students at random. The books they prefer are in the table. What percent of the students prefer mysteries? The denominator is the total surveyed 40 x z 100 3/4 The numerator is how many prefer mysteries =

Example 7-3a BOOKS The student council is trying to decide what types of books to sell at its annual book fair to help raise money for the eighth-grade trip. It surveys 40 students at random. The books they prefer are in the table. What percent of the students prefer mysteries? 12 preferred mysteries 40 x z 100 3/4 = 8short stories 11sports 9adventure novel 12mystery Number of Students Book Type 12

Example 7-3a BOOKS The student council is trying to decide what types of books to sell at its annual book fair to help raise money for the eighth-grade trip. It surveys 40 students at random. The books they prefer are in the table. What percent of the students prefer mysteries? Cross multiply 40 x z 100 3/4 = 12 40x= 12(100) Multiply 40x = 1200 Ask “What is being done by the variable?” The variable is being multiplied by 40 Do the inverse on both sides of the equal sign

Example 7-3a BOOKS The student council is trying to decide what types of books to sell at its annual book fair to help raise money for the eighth-grade trip. It surveys 40 students at random. The books they prefer are in the table. What percent of the students prefer mysteries? Using a fraction bar, divide both sides by 40 40 x z 100 3/4 = 12 40x= 12(100) 40x = 1200 40 Combine “like” terms 1  x = 30 Use the Identity Property to multiply 1  x x = 30 Add dimensional analysis % Answer:

Example 7-3b PENS The student shop sells pens. It surveys 50 students at random. The pens they prefer are in the table. What percent of the students prefer gel pens? 10roller balls 10glitter pens 8ball point 22gel pens NumberType Answer: x = 44% 3/4

Example 7-4a BOOKS The student council is trying to decide what types of books to sell at its annual book fair to help raise money for the eighth-grade trip. It surveys 40 students at random. The books they prefer are in the table. If 220 books are to be sold at the book fair, how many should be mysteries? 8short stories 11sports 9adventure novel 12mystery Number of Students Book Type Write proportion 4/4

Example 7-4a BOOKS The student council is trying to decide what types of books to sell at its annual book fair to help raise money for the eighth-grade trip. It surveys 40 students at random. The books they prefer are in the table. If 220 books are to be sold at the book fair, how many should be mysteries? 8short stories 11sports 9adventure novel 12mystery Number of Students Book Type First ratio is taken from the chart about the survey 4/4 12

Example 7-4a BOOKS The student council is trying to decide what types of books to sell at its annual book fair to help raise money for the eighth-grade trip. It surveys 40 students at random. The books they prefer are in the table. If 220 books are to be sold at the book fair, how many should be mysteries? 8short stories 11sports 9adventure novel 12mystery Number of Students Book Type Total surveyed is denominator 4/4 12 40

Example 7-4a BOOKS The student council is trying to decide what types of books to sell at its annual book fair to help raise money for the eighth-grade trip. It surveys 40 students at random. The books they prefer are in the table. If 220 books are to be sold at the book fair, how many should be mysteries? The next ratio will be based on how many actually were sold 4/4 12 40 The total books sold will be the denominator 220 = Define the variable x

Example 7-4a BOOKS The student council is trying to decide what types of books to sell at its annual book fair to help raise money for the eighth-grade trip. It surveys 40 students at random. The books they prefer are in the table. If 220 books are to be sold at the book fair, how many should be mysteries? 4/4 12 40220 = x Cross multiply 40x= 12(220) Multiply 40x = 2,640 Ask “What is being done by the variable?” The variable is being multiplied by 40 Do the inverse on both sides of the equal sign

Example 7-4a BOOKS The student council is trying to decide what types of books to sell at its annual book fair to help raise money for the eighth-grade trip. It surveys 40 students at random. The books they prefer are in the table. If 220 books are to be sold at the book fair, how many should be mysteries? 4/4 12 40220 = x 40x= 12(220) 40x = 2,640 Using a fraction bar, divide both sides by 40 40 Combine “like” terms 1  x = 66 Use the Identity Property to multiply 1  x x = 66 Add dimensional analysis mystery books Answer:

Example 7-4b PENS The student shop sells pens. It surveys 50 students at random. The pens they prefer are in the table. If 300 pens are to be sold at the student shop, how many should be gel pens? 10roller balls 10glitter pens 8ball point 22gel pens NumberType Answer: x = 132 gel pens * 4/4

End of Lesson 7 Assignment Lesson 8:7 Statistics: Using Sampling to Predict 3 - 15 All

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