Question

Augusto wants to prove to his parents that watching TV while he does his homework will help him get better grades. He decides to ask 20 of his friends if they watch TV while they do their homework and what their grades are. He finds that his friends who have high grades also watch TV while they do their homework. He tells his parents that he has proven that watching TV while doing homework will cause his grades to improve. What mistake has Augusto made?

Answer 1

He did not use a random sample, and he tried to show cause and effect with an observational study.

He did not use a random sample, and he tried to show cause and effect with an experiment.

He did not separate his friends into different groups, and he didn't apply a treatment.

He did not separate his friends into different groups, and he used a survey to collect data.

Answer 2

He do don't try out his theory himself. It may work for some people but it may not work for him

Answer 3

That makes sense, but it isn't any of the answer choices. I'm stuck between a and c

Answer 4

The first one

Answer 5

I think, I'm sorry

Answer 6

UGH i hate these questions.. is there anyone you could tag that might know?

Answer 7

Ummm... I think that the first a is the choice. If I were you I would I pick that one

Answer 8

Oh ummm...

Answer 9

Hold on

Answer 10

Thank you! I just want other people's point of view too, since this isn't something i can do again

Answer 11

@jim_thompson5910

Answer 12

He also has his email on his profile, so if he isn't online anymore, you can email him

Answer 13

Thanks :) Can you help with another one?

Answer 14

Oh nvm i got it!

Answer 15

Yay! Good for you! I could always help! Just tag me😝😝

Answer 16

In a study of 235 adults, the mean heart rate was 82 beats per minute. Assume the population of heart rates is known to be approximately normal with a standard deviation of 5 beats per minute. What is the 98% confidence interval for the mean beats per minute? @Samantha1lehman

Answer 17

I think it's C

80.9 – 86.3

70.9 – 83.3

81.2 – 82.8

80.9 – 83.3

Answer 18

Okay gimme a second to check back at my notes

Answer 19

Okay thank you :)

Answer 20

Yup!! It's C

Answer 21

thank you!

Answer 22

Nice job!!

Answer 23

thanks! I'm still scared to put the answer to the other question, gut feeling

Answer 24

Hahahahaha, I feel you! Did you ask jim_thompson5910? He knows a lot of answers to questions

Answer 25

No I didnt, i'm scared that if I email him he won't reply in time! @jim_thompson5910 please answer pleeeeease!!!

Answer 26

Okay I was looking back at that earlier question, and I think it's A because in the question, it said that the people who got good grades also watch tv while doing homework. Meaning there were people who got good grades and bad grades. He did separate them into those two subgroups. So it has to be A

Answer 27

Hmmm yeah that makes sense.

Answer 28

Oh I think he's viewing the question! So lets see

Answer 29

you're on this one right?

"In a study of 235 adults, the mean heart rate was 82 beats per minute. Assume the population of heart rates is known to be approximately normal with a standard deviation of 5 beats per minute. What is the 98% confidence interval for the mean beats per minute?"

Answer 30

But again, whatever you feel is best

Is this for homework?

Answer 31

No, the first question I asked. But if you can give me your viewpoint on that one too that'd be fine! lol

Answer 32

Yeah but the class is online so i dont get a do over and i'm on borderline to get a b so I don't wanna go down i'm almost done with the class!

Answer 33

well first off, he asked his friends and didn't do a random sample

so that's a big mistake right there

Answer 34

he didn't gather a representative sample and the sample is too small

Answer 35

he also doesn't have a control group

so he's definitely not doing an experiment

Answer 36

So it's an observational?

Answer 37

yes, you need to have 2 groups (control and experimental) to perform an experiment

Answer 38

So it's C? or D?

Answer 39

neither

Answer 40

there's a much bigger problem: he didn't use a random sample

he simply asked his friends this is definitely a biased study

Answer 41

Wow i'm so confused..... this question seemed so simple :(

Answer 42

he should have picked more people and picked them more randomly

ideally he would pick them out of a hat and more than likely they wouldn't be his friends

Answer 43

so it's A?

Answer 44

yes

Answer 45

thank you! Can you help with one more?

Answer 46

sure

Answer 47

A survey of 1,200 men and women asked, "Do you earn over $75,000 per year?" The table below shows the responses for males and females:

Answer 48

Male Female Total
Income over $75,000 585 485 1,070
Income below $75,000 65 65 130
Total 650 550 1200

Answer 49

Based on these data, are "being female" and "earning over $75,000" independent events?


No, P(being female | the person earns over $75,000) = P(being female)

No, P(being female | the person earns over $75,000) ≠ P(being female)

Yes, P(being female | the person earns over $75,000) = P(being female)

Yes, P(being female | the person earns over $75,000) ≠ P(being female)

Answer 50

@jim_thompson5910 Sorry it's messy :/

Answer 51

what is P(being female) equal to

Answer 52

Would It be D?

Answer 53

i'm stuck between d and c

Answer 54

b*

Answer 55

what is P(being female) equal to

Answer 56

the probability?

Answer 57

yes

Answer 58

you randomly pick a person, what's the chance of them being female?

Answer 59

550?

Answer 60

out of 1200

Answer 61

550/1200 = 0.45833333333333

Answer 62

now let's focus on just the people making over $75,000

you pick one of those people, what are the chances they are female?

Answer 63

485/1070

Answer 64

485/1070 = 0.45327102803739

Answer 65

so

P(being female) = 0.45833333333333
P(being female | earning more than $75,000) = 0.45327102803739

Answer 66

are they equal?

Answer 67

no, so they're independent?

Answer 68

nope, they have to be equal to be independent

Answer 69

Based on these data, are "being female" and "earning over $75,000" independent events?

No, P(being female | the person earns over $75,000) ≠ P(being female)

Answer 70

So it's b

Answer 71

cause it can't equal

Answer 72

basically this tells us that if you earn more than $75,000 then the probability of you being female is altered (or vice versa)

Answer 73

mmmm, okay I understand now! thank you!

Answer 74

np