algebra samples ppt

8/15/2019 Algebra Samples PPT

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6.4SELECT AND DRAW

CONCLUSIONS FROM

SAMPLES



Important Vocabulary

Population – A group of people or

objects that you want information about

Sample – a subset of the population

Unbiased Sample – representative of

the population you want information

about

Biased Sample – A sample thatunderrepresents of over represents part

of a population



Types of Samples

Self-Selected – Members of the

population can volunteer to be in the

sample

Systematic – a U!" is used to select

member of a population

#onvenience – "asy to reach members

of a population are selected andom – "ach member of a population

has an e$ual chance of being selected



Identifying Samples

A business reporter wants to survey wor%ers

about where they eat lunch during a typical wor%

wee%& 'dentify the type of sample described&

A( )he reporter writes a column as%ing wor%ers

to call a special phone number and identify

where they eat lunch during a typical wor% wee%&Self Selected

B( )he reporter as%s everyone in the newsroom

where they eat lunch during a typical wor% wee%&#onvenience



A real estate agent wants to %now if first-

time home buyers used the 'nternet to

research home listings& )he real-estate

agent calls every fifth first-time home buyerand as%s them if they used the 'nternet to

research home listings& 'dentify the type of

sample described

- Systematic



*& A team wants to %now who the fans thin% was the team+s

most valuable player during the season& ,ans can vote on the

team+s website&

- Self Selected Unbiased.Biased(/&)he managers of a movie theater chain want to find the

number of movies people in the community usually see in a

theater each month& )he managers have the tic%et sellers at

each theater survey customers when they purchase theirtic%ets&

- #onvenience Biased(

0& )he managers of a company with 122 employees want to

%now how the employees feel about some proposed changes

to employee policies& )he managers use a computer to

generate a list of 12 employees to survey from a database

that includes all of the employees&

- andom Unbiased(



3& A consumer advocacy group wants to %now if car

owners believe their car is reliable& )he group randomly

selects *2/2 car owners and mails out a survey to each

one&- andom.Self Selected4 Unbiased(

1& A grocery store wants to %now which day of the wee%

consumers prefer to do their grocery shopping& "veryone

who shops at the store on ,riday is as%ed which day ofthe wee% they prefer to do their grocery shopping&

- #onvenience Biased(

5& A survey of students+ favorite school subjects is being

conducted& "very other student in the math club is as%ed67hich school subject is your favorite48

- Systematic Biased(



Margin of Error

9ives a limit on how much the

responses of a sample would differ from

the responses of a population&

As sample si:e increases; the margin oferror decreases&

1M.O.E. =

n

±



Find the Margin of Error

9iven the Sample Si:e<

*&( =*20

> ?.- *&/ @

/&( 1=22

> ?.- *&0@

0&( */;222

> ?.- 2&@



Find the Sample Size

9iven the Margin of "rror<

*&( *&/@

> 533 People

/&( 3&5@

> 3=0 People



A survey claims that the percent of an entire

population that agrees with redeveloping the city

par% is li%ely between 3&*@ and 1=&1@& )heremainder of the people in the survey were

against redevelopment&

a&( ow many people were surveyed4

- about 15= People

b&( ,ind the interval that is li%ely to contain the

eCact percent of people in the population againstredevelopment&

- Between 3/&1@ and 12&@



6.5 Sureys! E"periments #$bserational Studies

"Cperiment – 'mposes a treatment on

individuals in order to collect data on

their response to the treatment

#ontrolled – has two groups with identicalconditions eCcept one variable

#ontrol 9roup ordinary conditions( vs )reatment

9roup subject to variable(

andomi:ed #omparative "Cperiment – individualsare randomly assigned to control or treatment group&



Vocab. %ontinued&.

Dbservational Study – observes

individuals and measures variables

without controlling the individuals or their

environment&

Biased Euestions – Euestions that lead

to inaccurate results



E"plain the 'ias&

A survey $uestion as%s; 6Are you in favor of

closing the library; our town+s most historic

and valuable resource; one day a wee% to

reduce taCes48 )ell why the $uestion may bebiased or otherwise introduce bias into the

survey& Fescribe a way to correct the flaw&

Answer - )he wording of the $uestion implies that closing thelibrary one day a wee% is the wrong thing to do& A better

$uestion is 6Are you in favor of closing the library one day a

wee% to reduce taCes48



E"periment s. $bserationalStudy

*& A professional painter wants to determine whether a paint additive will eliminate

brush and roller mar%s on walls& She paints / walls with the additive and / walls

without the additive without %nowing which paint contains the additive&"Cperiment

/& A veterinarian studies the effectiveness of a flea-and-tic% protection that is

applied to dogs once a month by monitoring 12 randomly selected dogs that

already use the protection and 12 randomly selected dogs that do not use the

protection

Dbservational Study

0& Gou want to %now if students in your class will finish their math homewor% faster

if they are allowed to use calculators&

"Cperiment

3& Gou want to %now if grocery stores in the city have higher prices than grocery

stores in suburbs of the city&

Dbservational Study

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