Question

Based on these data, are "being female" and "earning over $50,000" independent events

Answer 1

If independent probablity of both should equal probablity of first times the probability of the second.

Answer 2

so they aren't ?

Answer 3

Well lets see in your case also could see if P(female)= P(female given earn 50,000)

Answer 4

so 450/1000 compared to 375/850

Answer 5

45% and 44%

Answer 6

so they are not equal

Answer 7

hmm close, but technically I guess we would say they aren't equal

Answer 8

so d?

Answer 9

I would go with d, but if i got a second choice I would then try a.

Answer 10

ok, could u help with a couple more?

Answer 11

Sure

Answer 12

The grades on the last science exam had a mean of 89%. Assume the population of grades on science exams is known to be distributed normally, with a standard deviation of 14%. Approximately what percent of students earn a score between 75% and 89%?

first of all is this 34.1

Answer 13

I believe so because that is from 1 sd below the mean to the mean.

Answer 14

okay

Answer 15

I would say it is significant since the difference is unlikely

Answer 16

Alice wants to prove to her parents that listening to music while she does her homework will help her get better grades. She decides to ask 25 of her friends if they listen to music while they do their homework and what their grades are. She finds that her friends who have high grades also listen to music while they do their homework. She tells her parents that she has proven that listening to music while doing homework will cause her grades to improve. What mistake has Alice made?

She did not separate her friends into different groups, and she didn't apply a treatment.
She did not separate her friends into different groups, and she used a survey to collect data.
She did not use a random sample, and she tried to show cause and effect with an observational study.
She did not use a random sample, and she tried to show cause and effect with an experiment.
i picked c for this what do you think

Answer 17

I would lean towards that

Answer 18

She didn't have a control group

Answer 19

What grades did people get that didn't listen to music.

Answer 20

Be back in five minutes.

Answer 21

okay

Answer 22

Arlene is testing whether school is more enjoyable when students are making high grades. She asked 100 students if they enjoyed school and whether their GPA was above or below 3.0. She found that 30 of the 40 students with a GPA above 3.0 reported that they enjoyed school, and 15 of the 60 students with a GPA below 3.0 reported that they enjoyed school. What is the probability that a student with a GPA below 3.0 does not enjoy school?
last one

Answer 23

ok back

Answer 24

hey

Answer 25

Well looks like there were 60 asked and 15 said they did so I would say the rest didn't

Answer 26

so just 15/60?

Answer 27

no the rest so 45/60

Answer 28

ohh okay, do you have time to help with 4 free response?

Answer 29

I think so

Answer 30

you rock!

Answer 31

Ok similar to the problem you had earlier, if it is fair the probablility of being in the honor roll should be the same as the probability of being in the honor roll and being in the class requested.

Answer 32

ok I'm just not sure what values to use for the ratios

Answer 33

Well for one the probability of being in honor roll in general which is 356/500

Answer 34

so 71%

Answer 35

The other is looking at students that got the class they wanted and how many of them are honor roll

Answer 36

Yeah approx 71%, so the other will be 315/379

Answer 37

so 83%

Answer 38

or approx 83%

Answer 39

Yeah those are fairly different so there may be some credence in saying you are more likely to get the class you want if you are in the honor roll.

Answer 40

so then how would u answer the question ?

Answer 41

Er what I just said

Answer 42

did we ever see how many did not get the class they wanted?

Answer 43

No but if you wanted we could try that viewpoint also.

Answer 44

i think thats what the question is asking for

Answer 45

Fairness could be looked at from either view point.

Answer 46

like seeing if being on honor roll or not gets you the classes you request

Answer 47

maybe i am wrong.

Answer 48

But if you wanted to go that way sure so once again, 71% were in the honor roll

Answer 49

of those who did not get the class they wanted what percent were in honor roll.

Answer 50

64

Answer 51

I get 41/121 or 34%

Answer 52

So we could also say that fewer students got classes they didn't want if they were in the honor roll.

Answer 53

Again if the system was fair this should have been 71%

Answer 54

OK cool

Answer 55

want me to put new question in new thread?

Answer 56

I'm fine either way, if you have fellow students here may make it easier for them to find the problems.