Daniellelovee
  • Daniellelovee
For election polling, a simple random sample of 850 registered voters in District X shows that 58% favor Candidate A, and a simple random sample of 1400 registered voters in District Y shows that 53% favor Candidate A If District Y is Group 2, what are the values of tcrit, pˆ2 , and n2 for a 90% confidence interval?
Mathematics
  • Stacey Warren - Expert brainly.com
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SOLVED
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schrodinger
  • schrodinger
I got my questions answered at brainly.com in under 10 minutes. Go to brainly.com now for free help!
Daniellelovee
  • Daniellelovee
@Directrix
Directrix
  • Directrix
|dw:1450240669064:dw|
Directrix
  • Directrix
^^^^

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Daniellelovee
  • Daniellelovee
.02155.
Daniellelovee
  • Daniellelovee
no wait I got 0.69
Daniellelovee
  • Daniellelovee
@Directrix
Directrix
  • Directrix
What is .58 - .53 = This would be d.
Directrix
  • Directrix
Use the difference between the sample proportions and the margin of error to construct the confidence interval (d− margin of error, d+ margin of error) Is that this: (.05 - .69, .05 + .69) I will double-check the .69 just in case.
Directrix
  • Directrix
Look at this. I got .035 where you got >>no wait I got 0.69 The Wolf cranked out: http://www.wolframalpha.com/input/?i=1.64*sqrt%28%28.58%28.42%2F850%29%29+%2B+%28.53%28.47%29%29%2F1400%29%29
1 Attachment
Directrix
  • Directrix
Use the difference between the sample proportions and the margin of error to construct the confidence interval (d− margin of error, d+ margin of error) Is that this: (.05 - .035, .05 + .035) = (.015 , .085)
Daniellelovee
  • Daniellelovee
i can give you my options if that helps
Directrix
  • Directrix
tcrit, pˆ2 , and n2 for a 90% confidence interval? 1.64, .53, 1400
Directrix
  • Directrix
Post them and let's see. I do not have an intuitive feel for what is going on with this problem.
Daniellelovee
  • Daniellelovee
(1.5, 8.5) (0.3, 9.7) (0.8, 9.2) (2.8, 7.2)
Daniellelovee
  • Daniellelovee
@Directrix
Directrix
  • Directrix
On my first attempt, I got this; (.015 , .085)
Directrix
  • Directrix
My decimal points are off.
Daniellelovee
  • Daniellelovee
yeah and the first number seems odd compared to my options
Directrix
  • Directrix
Maybe you can find my error. I think you made an error on the first calculation of the giant square root.
Daniellelovee
  • Daniellelovee
is possible is that the square got cut off and I couldnt see the number you marked there
Daniellelovee
  • Daniellelovee
can you put the equation again just smaller? @Directrix
Directrix
  • Directrix
Smaller Equation Attached
Daniellelovee
  • Daniellelovee
oh ok then I got 0.02155 @Directrix
Directrix
  • Directrix
I don't see an error here: http://www.wolframalpha.com/input/?i=1.64*sqrt%28%28.58%28.42%2F850%29%29+%2B+%28.53%28.47%29%29%2F1400%29%29
Daniellelovee
  • Daniellelovee
then B is the best choice based on that calculator
Daniellelovee
  • Daniellelovee
right?
Daniellelovee
  • Daniellelovee
@Directrix
Directrix
  • Directrix
When you cranked out the square root "thing," did you do the square roots individually and then add? The square root of a sum is not the sum of the square roots. The Wolf sometimes messes up.
Daniellelovee
  • Daniellelovee
ok im going to check one more time lets see if I get a good answer this time
Daniellelovee
  • Daniellelovee
I got 0.35 this time
Directrix
  • Directrix
Read the text. This has to be done to get the answer: margin of error to construct the confidence interval (d− margin of error, d+ margin of error) That square root "thing" is the margin of error.
Daniellelovee
  • Daniellelovee
(0.05 - 0.035, 0 .05 + 0.035) =(0.015 , 0.085)
Daniellelovee
  • Daniellelovee
@Directrix
Directrix
  • Directrix
That is not an option. (.015 , .085) is what I got on the first round.
Daniellelovee
  • Daniellelovee
then idk :(
Directrix
  • Directrix
Look at the problem you posted. Is the confidence interval supposed to be 95%? You wrote 90%.
Directrix
  • Directrix
From @Teddy_the_Tudor_Brit Construct a 95% confidence interval for the difference between the percent of all registered voters in District X and District Y who prefer Candidate A. (0.3, 9.7) (0.8, 9.2) (1.5, 8.5) (2.8, 7.2) Edit Answer: ANS:- For District X, N = 850 P = 0.58 Mean = np = 850*0.58 = 493 Sd = sqrt(n*p*(1-p)) = sqrt(850*0.58*(1-0.58)) = 14.39 For District Y, N = 1400 P = 0.53 Mean = np = 1400*0.53 = 742 Sd = sqrt(n*p*(1-p)) = sqrt(1400*0.53*(1-0.53)) = 18.68 So 95% confidence interval for the difference between the percent of all registered voters in District X and District Y who prefer Candidate A is (742-498) +/- 1.64*sqrt((850*14.39+1140*18.68)/(1140+850)) = (0.8, 9.2) http://tutorteddy.com/site/free_stat_help1.php/NjM3Nw==/For-election-polling-a-simple-random-sample-of-850-registered-voters-in-District-X-shows-that-58--f
Directrix
  • Directrix
Teddy the Brit Tudor has this option in his list as do you: (1.5, 8.5)
Daniellelovee
  • Daniellelovee
that name reminded me of the Tudors and can that person prove it?
Daniellelovee
  • Daniellelovee
that A is the correct choice?
Directrix
  • Directrix
Play on the word Tudor to remind us of our fuzzy studies.
Daniellelovee
  • Daniellelovee
lol yeah but I did love the Tudors story and Elizabeth's diary
Directrix
  • Directrix
Teddy the Brit Tudor can't prove anything. I think there is a step to our calculations that is missing.
Daniellelovee
  • Daniellelovee
so then he/she just guessed?
Directrix
  • Directrix
Did you not see the work?
Daniellelovee
  • Daniellelovee
omg no sorry hold on let me check it
Daniellelovee
  • Daniellelovee
omg i messed up big time those where the option for the next question omg im so terribly sorry
Daniellelovee
  • Daniellelovee
zcrit=1.64, ^p2=53%, n2=742 zcrit=2.58, ^p2=57%, n2=742 zcrit=1.64, ^p2=53%, n2=1400 zcrit=3.58, ^p2=53%, n2=1400
Daniellelovee
  • Daniellelovee
zcrit=1.64, ^p2=53%, n2=742 zcrit=2.58, ^p2=57%, n2=742 zcrit=1.64, ^p2=53%, n2=1400 zcrit=2.58, ^p2=53%, n2=1400 @Directrix
Directrix
  • Directrix
An hour ago, I posted this as the answer to the question as it appeared in the first region: tcrit, pˆ2 , and n2 for a 90% confidence interval? 1.64, .53, 1400
Daniellelovee
  • Daniellelovee
thank you for your help and again im so sorry for messing up
Directrix
  • Directrix
zcrit=1.64, ^p2=53%, n2=1400 OMG! It's okay. I think we may have part of the answer to the next question. Not sure.
Directrix
  • Directrix
Now, you can sleep.
Daniellelovee
  • Daniellelovee
lol no I still have more question if you don't mind this lesson was pretty hard
Directrix
  • Directrix
I lost an hour and a half of my life on this problem. You can post the new problem in a new thread. This thread is jinxed.
Daniellelovee
  • Daniellelovee
lol that actually made me laugh, im sorry, and I was planning on doing a new thread either way

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