Probability Formula for Testing Joe's Claim in a Statistics Class

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Discussion Overview

The discussion revolves around the statistical analysis of Joe's claim regarding the percentage of students in his statistics class who will receive an A on the final examination. Participants explore the appropriate statistical formula to use for testing this claim, considering the sample size and significance level. The conversation touches on concepts of hypothesis testing and the implications of sample size on statistical conclusions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • Joe claims that no more than 20% of students will get an A, and he sampled 35 students, finding that 30% received an A.
  • Some participants question whether the total size of Joe's class is large, suggesting that a small class size could affect the results.
  • There is confusion regarding whether Joe's sample of 35 students represents the entire class or if it is a sample from a larger class.
  • One participant emphasizes that if Joe's entire class consists of only 35 students, then the percentage of students getting A's exceeds 20% based on the sample results.
  • Another participant argues that the question is incomplete and that assumptions about class size are necessary to determine the appropriate formula.

Areas of Agreement / Disagreement

Participants express differing views on the interpretation of the sample size and its implications for the statistical analysis. There is no consensus on the correct approach or formula to use, as the discussion remains unresolved regarding the assumptions needed for the analysis.

Contextual Notes

Limitations include the ambiguity surrounding the total class size and the implications this has for the statistical testing. The discussion highlights the need for clarity in defining the population from which the sample is drawn.

doug123
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Joe thinks that no more than 20% of students in his statistics class will get an A in the final examination. To prove his claim, he takes a random sample of 35 students and finds to his surprise that 30% of his students got an A. At a .01 percent level of significance can we reject Joe's view?

I do not want the answer to this question, I would just like to know what formula to use, and why. Thank you so much I really appreciate it.
 
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Are we to assume that the total size of Joe's class is very large? If his class only has 40 students in it that would affect the result.
 
no he has 35 students in his class, I put that in the question, however I am curious as to the formula to use
 
No, you said he took a random sample of 35 students. If he only HAS 35 students then you can say with certainty that more than 20% of his students got A's.
 
okay i really don't understand what your saying, all i want to know is what equation to use that's all. Thanks
 
Doug, the way you phrased your question "...he takes a random sample of 35 students ..." suggests that his SAMPLE contains 35 students and that the size of the class is unspecified.

If I may reword:


"Joe thinks that no more than 20% of students in his statistics class will get an A in the final examination. To prove his claim, he takes a random sample (eg. n=5 or n=10) from the 35 students in the class and finds to his surprise that 30% of his students got an A. At a .01 percent level of significance can we reject Joe's view?

He took ".
 
NO, he took a random sample OF 35 students, not he took a random sample from 35 students. So to explain this he basically took 35 students and found that 30% of those 35 students got an A. It isn't that difficult to understand. If anyone knows the formula to use I would appreciate it. Thanks for all of your help anyway though.
 
Doug, there is no formula for that because the question is incomplete. You have to either assume that his class size is very large, or you have to say how large it actually is.
 

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