Calculating Probabilities without Standard Deviation
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I need some guidance in how to calculate probabilities without knowing the std deviation.
Population = 3005
calculate P(x-bar > 50.8) for sample size of n = 253
calculate P(x-bar > 50.6) for sample size of n = 134
calculate P(x-bar > 51) for sample size of n = 119
Then combine the two probabilities 51 and 50.6 into one using the concept of independent events.
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The solution calculates probabilities without standard deviation.
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I need some guidance in how to calculate probabilities without knowing the std dev. I am struggling with the correct formula...
Population = 3005
(1) calculate P(x-bar > 50.8) for sample size of n = 253
(2) calculate P(x-bar > 50.6) for sample size of n = 134
(3) calculate P(x-bar > 51) for sample size of n = 119
Then combine the two probablities 51 and 50.6 into one using the concept of independent events.
Guidance would be appreciated.
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Hi, regarding your questions, I would like to give you the following guidance.
First of all, since you did not provide any detailed information for each of samples (with size n=253, 134, and 119, respectively), I could not provide with you a ...
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- BSc , Wuhan Univ. China
- MA, Shandong Univ.
Recent Feedback
- "Your solution, looks excellent. I recognize things from previous chapters. I have seen the standard deviation formula you used to get 5.154. I do understand the Central Limit Theorem needs the sample size (n) to be greater than 30, we have 100. I do understand the sample mean(s) of the population will follow a normal distribution, and that CLT states the sample mean of population is the population (mean), we have 143.74. But when and WHY do we use the standard deviation formula where you got 5.154. WHEN & Why use standard deviation of the sample mean. I don't understand, why don't we simply use the "100" I understand that standard deviation is the square root of variance. I do understand that the variance is the square of the differences of each sample data value minus the mean. But somehow, why not use 100, why use standard deviation of sample mean? Please help explain."
- "excellent work"
- "Thank you so much for all of your help!!! I will be posting another assignment. Please let me know (once posted), if the credits I'm offering is enough or you ! Thanks again!"
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- "Thank you very much for your valuable time and assistance!"
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