Question

A researcher posts a radio advertisement offering $35 in exchange for participation in a short study. The researcher accepts the first eight people who respond to the advertisement. Which of the following statements is true about the sample?

It is a valid sample because the first eight people were selected to participate.
It is not a valid sample because it is not a random sample of the population.
It is a valid sample because money was offered to participants.
It is not a valid sample because it is only a short study.

Answer 1

@Vocaloid

Answer 2

@Vocaloid

Answer 3

@Empty

Answer 4

u still need help

Answer 5

yes :)

Answer 6

ok semme see here

Answer 7

what?

Answer 8

its not b

Answer 9

not a

Answer 10

it's not a valid sample since it's not a random sample...

Answer 11

i say d

Answer 12

but it is random

Answer 13

nope

Answer 14

they let the first 8 in they come randomly

Answer 15

it's a voluntary response sample

Answer 16

http://stattrek.com/statistics/dictionary.aspx?definition=Voluntary%20sample

Answer 17

by definition, if participants volunteer to be part of a sample, then by definition it is not random.

Answer 18

so b?

Answer 19

yes

Answer 20

The track-and-field coach wants to know whether the students in the entire school prefer track races or field events. The coach draws a random sample from the following groups:

All students in each grade
All teachers in the school
All boys in each grade in the school
All students on the track-and-field team
Which group best represents the population she should take a random sample from to get the best results for her survey?
All students in each grade
All teachers in the school
All boys in each grade in the school
All students on the track-and-field team

Answer 21

hint: he wants to know about all the students in the school

Answer 22

a

Answer 23

A?

Answer 24

yes

as a hint for the future, the sample should match the population as closely as possible

Answer 25

Jacob wants to know how many students in his school enjoy watching space travel programs on TV. He poses this question to all 20 students in his history class and finds that 80% of his classmates enjoy watching space travel programs on TV. He claims that 80% of the school's student population would be expected to enjoy watching space travel programs on TV. Is Jacob making a valid inference about this population?

No, it is not a valid inference because his classmates do not make up a random sample of the students in the school
No, it is not a valid inference because he asked all 20 students in his history class instead of taking a sample from his math class
Yes, it is a valid inference because his classmates make up a random sample of the students in the school
Yes, it is a valid inference because he asked all 20 students in his history class

Answer 26

@Vocaloid

Answer 27

any thoughts? this is very similar to the other problem from before

Answer 28

c?

Answer 29

nope, think carefully

Answer 30

d

Answer 31

nope

Answer 32

hint: he only sampled students from his history class, not the entire school

Answer 33

b

Answer 34

no. read what I wrote carefully.

Answer 35

A

Answer 36

@Vocaloid

Answer 37

right...

Answer 38

@Vocaloid

Answer 39

any ideas? look at the numbers in the table and see which statement makes sense...

Answer 40

A?

Answer 41

@Vocaloid

Answer 42

nope. read all the statements and see which one matches the data.

Answer 43

c?

Answer 44

good.

Answer 45

again, look at the data carefully, then see which statement matches...

Answer 46

d?

Answer 47

great.

Answer 48

@Vocaloid

Answer 49

start by finding the mean of sample A and the mean of sample B

Answer 50

how?

Answer 51

@Vocaloid

Answer 52

do i just add the nnumbers?

Answer 53

for sample A, find

the number of adults who work 6 hours)*6 + (the number of adults who work 7 hours)*7, etc. until 10, then divide that by 500

Answer 54

ok.....

60 * 6 + 90 * 7 + 145 * 8 + 150 * 9 + 55 * 10 / 500 = 8.1

Answer 55

@Vocaloid

Answer 56

@Vocaloid

Answer 57

good now do the same thing w/ sample B

Answer 58

i got 8.11 @Vocaloid

Answer 59

great.

Answer 60

so both means are closer to 8 than 9, meaning that Ryan is correct.

Answer 61

ok next! :)

Answer 62

@Vocaloid

Answer 63

again, find the mean.

Answer 64

add the numbers up and divide by the number of families

Answer 65

wait how can you give me the equation ? @Vocaloid

Answer 66

start by finding the mean of Neighborhood Q. add the numbers in the row, then divide by the number of families.

Answer 67

you know how to add and divide, right? ....

Answer 68

yes

Answer 69

good now find the mean of Neighborhood Q.

Answer 70

6 + 3 + 1 + 2 + 3 + 2 +5 +1 +2 / 9 = 2.777777778

Answer 71

great now find the mean of the other neighborhood.

Answer 72

5 + 2 + 4 + 3 + 5 + 3 + 2 + 4 + 5 / 9= 3.6666667

Answer 73

great. now, the neighborhood with the bigger mean has the larger family sizes, on average.

Answer 74

so neighborhood s

Answer 75

great

Answer 76

@Vocaloid

Answer 77

pick the group where most of the dots are to the left

Answer 78

group A

Answer 79

@Vocaloid

Answer 80

@Vocaloid

Answer 81

great

Answer 82

A scale on a map shows that 2 inches = 25 miles.

Part A
How many inches on the map represent 60 miles?

Enter your answer in the box.


inches
Part B
How many miles are represented by
1
4
inch on the map?

Enter your answer in the box.


miles

Answer 83

@Vocaloid

Answer 84

set up a proportion and solve for x