Question

Statistics word problem! :)
http://puu.sh/6Z5pY.png

Answer 1

@jim_thompson5910

Answer 2

This seems to me like a binomial distribution problem.

Answer 3

It is! It's what I'm learning right now but I'm not 100% on it:)

Answer 4

What did you get for the first bullet?

Answer 5

Also, do you have a probability distribution chart for when n = 50 for this?

Answer 6

No i don't, this is all that was given. I just started taking statistics and this is my 2nd assignment haha so please understand i don't understand a lot

Answer 7

No worries. I was just wondering because that would make some of these parts much easier to calculate.
The formula we are using is \[\left(\begin{matrix}n \\ x\end{matrix}\right)p^xq ^{n-x}\]

Answer 8

I know this is coming back to me it's something like (0.24)^n*(0.76)^n-x

Answer 9

Right!

Answer 10

So what is n? 50?

Answer 11

so that it would be (0.24)^10*(0.76)^40?

Answer 12

Yes. The variable n represents the number of trials, which in this case is 50. That's right.

Answer 13

I was doing this and I had a problem with something so maybe you can help with that! On the 2nd bullet point it says it at least 10. I understand I have to do the ^0 up to ^10 but it takes so long, is there a shorter way to do it?

Answer 14

(0.24)^10*(0.76)^40 I know that's wrong because I'm getting over one, so what am I doing wrong?

Answer 15

The number .24^10 * .76^40 is not greater than 1

Answer 16

I'm getting 1.083068...*10^(-11) which is definitely less than 1.

Answer 17

Remember that you have to multiply by \[\left(\begin{matrix}50 \\ 10\end{matrix}\right)\]

Answer 18

Oh whoops! That's correct sorry:)

Answer 19

Okay so for #2 of it, it says less than 10. Do I have to do all of them or is there a way to do it without having to multiply them all out?

Answer 20

Without a distribution chart, the fastest way I know to do it is to add up all the probabilities 1 through 9 and subtract that value from 1.

Answer 21

http://www.statisticshowto.com/tables/binomial-distribution-table/

Answer 22

Look at this page and scroll down to n = 50.

Answer 23

Well actually, they don't have our .24 probability of success. Hold on.

Answer 24

Uh oh :P haha

Answer 25

http://stattrek.com/online-calculator/binomial.aspx

Answer 26

Check that out though. It does all the work for you. Remember that when we are talking about at least 10, we mean >= 10

Answer 27

what should I put for "number of success?"

Answer 28

0.24?

Answer 29

10

Answer 30

At least for bullets 1 - 3

Answer 31

so it would be bullet 1: 0.111255856065322
bullet 2: 0.206550433838689
bullet 3: 0.317806289904011

Answer 32

and bullet 4: 0.11628996701893859

Answer 33

Sorry for slow responses, openstudy doesn't like my computer @RBauer4

Answer 34

bullet 2 should be .7934.... , and bullet 1 and bullet 3 are correct.

Answer 35

At least implies greater than or equal to

Answer 36

OOo i did x>10 not x<10

Answer 37

Wording was weird :)
and bullet 4 I should do x=21 and x=45 and just add them

Answer 38

0.0022710274978721500000691282565252491

Answer 39

That doesn't seem right to me haha

Answer 40

Well, if you think about it. You practically have a probability of 1 considering the cumulative probability less than 45

Answer 41

Ooooh right then 0.002271.... would be considered "unusual"

Answer 42

Thus, we are only really calculating the probability when x is strictly greater than 20

Answer 43

So 0.11, 0.7934, 0.317, 0.11 and 0.0027

Answer 44

I think the last bullet would be 0.003769047260403 and I'm not sure for the 4th yet

Answer 45

And I believe bullet four is 0.78968051890090805

Answer 46

I must go now. Good luck in your studies

Answer 47

thanks!