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Hello! Here are a few statistics questions I am having trouble with.

Hello! Here are a few statistics questions I am having trouble with. Please help!

1.In a preliminary study, the sample standard deviation for the duration of a particular back pain suffered by patients was 18.0 months. How large a random sample is needed to construct a 90% confidence interval so that an estimate can be made within 2 months of the actual duration ?

2.In preparing a report on the economy, we need to estimate the percentage of businesses that plan to hire additional employees in the next 60 days. How many randomly selected employers must we contact in order to classify an estimate in which we are 98% confident, with an error of 5% ? 

Top Answer

1) we are given that  σ  = 18 margin error = 2 zalpha/2 = 1.645 at 90% confidence Now Sample size (zalpha/2 *... View the full answer

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Other Answers

Question 1 The sample size is given by n=(z* Sd/E) 2 where Sd is the standard deviation and E =margin... View the full answer

1 comment
  • Correction for question 2==> Hence n=0.25*(2.326/0.05)2 =542
    • Stat.Solve
    • Apr 04, 2018 at 9:10pm

1)  T h e   m i n i m u m   s a m p l e   s i z e... View the full answer

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