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Ms. Drake 7th grade Math
Measures of Central Tendency
Lesson 1Populations and Samples
Measures of Central Tendency Vocabulary
Bar graphBox- and-Whisker PlotCircle GraphCumulative FrequencyDouble Bar GraphFirst QuartileFrequency Table
Measures of Central Tendency Vocabulary
HistogramLine GraphLower ExtremeMeanMedianModeNegative CorrelationNo correlation
Measures of Central Tendency Vocabulary
OutlierPopulationPositive correlationRandom SampleRangeSample
Measures of Central Tendency Vocabulary
Scatter PlotSecond QuartileSectorStem-and-Leaf PlotThird QuartileUpper Extreme
Chapter 1
Populations and SamplesPopulation: The entire group of objects or individuals considered for a survey
Samples: A part of the population
All elementary
students make up a population.
Students from this particular
class are the sample.
Examples
Population: All lionsSample: Lions in a game preserve.
Example
Population: All customersSample: The customers who fill out a survey
Identify the Population and Sample in Each Situation
The decoration committee asks 25 students about
their ideas for a 7th grade party.
The population is the 7th grade. The
sample is the 25 students surveyed.
Identify the population and the sample in this situation.
A disc jockey asks the first ten listeners who call in if they like the last song that was played.
The population is all the listening public.The sample is the first ten listeners
Identify the population and the sample in this situation.
Researchers poll every fifteenth voter after a local
election.
The population is all the people who
voted. The sample is the fifteen voters that
were polled.
Random Sampling
For a sample to be useful, it must represent the population.
A random sample gives every member of the population an equal chance of being chosen.
The local grocery store wants to know if their customers are satisfied with their service.
.
The manager surveys the customers that
he knows personally
Tell whether each sampling method is random:
Tell whether each sampling method is random:
The manager surveys every tenth customer that
comes into the store on Friday morning.
Tell whether each sampling method is random:
The manager puts the names of all customers in a
hat and surveys the customers whose names he
draws.
Give a reason why each sampling method may not be random.
A reporter calls 100 people from the telephone book.
A researcher questions all of the customers at one of several entrances to a
supermarket.
Give a reason why each sampling
method may not be random.
A reporter surveys people who are using
an internet site
Until next time, try to come up with some other
ways that you can use what you know about
populations and samples.