AnswersCommon Core Math 7 - MA3107 CRInferences and Predictions

Multiple Samples Answers

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Eldrick manages wildlife samples for Ducks Unlimited. Two samples of duck populations at a migratory site are shown in the table below. Which statement about the samples is true?Duck Pond SamplesSample 1Sample 2Mallard21Mallard8Wood Duck4Wood Duck17Green Wing Teal9Green Wing Teal15American Widgeon6American Widgeon0

A
Eldrick can use both of these samples to find the mean frequency of each duck.
B
Eldrick should take another sample because there is too much variability in the two samples.
C
Eldrick should use only the first sample to find the mean frequency of each duck.
D
Eldrick should use only the second sample to find the mean frequency of each duck.
6

Braden wants to compare the types of ducks in two nearby ponds. He collected two samples using the following criteria. For sample 1, he counted the types of ducks on Walden Pond from 6 A.M. to 9 A.M. For sample 2, he counted the number of Mallard ducks that were on Brook’s Pond from 12 P.M. to 3 P.M. What would improve Braden’s plan? Select three options.

A
Braden should sample the ducks on each pond at the same time of day because animals are active at different times.
B
Braden should sample twice at each pond if he wants to make sure each sample is representative of the population.
C
Braden should count more than Mallard ducks on Brook’s Pond if he wants to compare the types of ducks on each pond.
D
Braden should only count Mallard ducks on Walden Pond so he counts the same types of ducks as he does at Brook’s pond.
E
Braden should include herons and geese in his samples because they also like ponds.
7

Josiah kept track of how many songs of each genre were played in an hour from his MP3 player. The counts are displayed in the table below. He has a total of 1,500 songs on his player. Josiah predicted the number of rock songs on his MP3 player to be 300 songs. Which statements about his solution are true? Select three choices.Josiah’s MusicSample 1Sample 2R & B5R & B4Pop4Pop3Classical3Classical5Jazz2Jazz4Rock6Rock4Josiah’s work:

Question illustration
A
He should have found the average of the number of rock songs by averaging 4 and 6 to get 5.
B
He did not multiply the numerator and denominator by the correct number to equal 1,500.
C
His answer will be one-half of what he got because he did not divide 10 by 2 when setting up the proportion.
D
He can only solve the proportion by multiplying the numerator and denominator by a common multiple.
E
He should have multiplied the numerator and denominator by 75, not 30, because .
Option E
8

The table displays the number of butterflies collected in a sample over three years. What inferences can be made from the samples taken on butterfly populations? Select three choices.Louden County Butterfly CountYear 1Year 2Year 3Zebra Swallowtail21Zebra Swallowtail10Zebra Swallowtail10Viceroy3Viceroy4Viceroy3Painted Lady2Painted Lady0Painted Lady16Monarch82Monarch52Monarch57

A
The average number of monarchs over all three samples is less than the number of monarchs counted in year 3.
B
The Viceroy population remained fairly steady over the three years recorded.
C
The average number of Zebra Swallowtails over all three samples will be less than the number recorded in year 1.
D
If a population is increasing over time, the average will be less than the most recent count.
E
There was a mistake in the sample for year 3 as the Painted Ladies were extinct in year 2.
9

The owner of a local restaurant surveyed her staff on their preference of uniform color. The results are displayed in the table below. Which pair of samples is most representative of the preference of all the staff?Uniform Color SurveySample 1Sample 2Sample 3Beige3Beige12Beige7Blue7Blue5Blue15Black10Black3Black18

A
Sample 1 and sample 2 are most representative because they are the same size.
B
Sample 1 and sample 3 are most representative because the relationship between preferences is consistent.
C
Sample 2 and sample 3 are most representative because the samples show a greater variability in preferences.
D
None of the samples are representative because none of the values remained constant.
10

DeWayne wants to find out what career his fellow middle school students would like to pursue. He plans to collect three samples. Which statements describe good methods for collecting the samples? Select two options..

A
Interview students at lunch because it is likely that students with different interests will be present.
B
Interview students in the art club because they are creative and will come up with fun answers.
C
Interview students in the robotics club because they are focused on academics and concerned about their future.
D
Interview students in English class because everyone has to take English, and he can reach a variety of students.
E
Interview students and provide only four choices so that the data does not get complicated.

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