stat. problem again, pls help

[匿名]

2009-06-10 4:14 am

4. A recent survey of 50 executives who were laid off from their
previous position revealed it took a mean of 26 weeks for them to find another position. Assume that the population standard deviation was 6.2 weeks.

a. What is the estimated population mean?

b. Construct a 95 percent confidence interval for the population mean.
c. Is it reasonable that the population mean is 28 weeks? Justify your
answer.

d. We want to estimate the population mean within 1.5 weeks, with a
99 percent level of confidence. How large a sample is required?

回答 (2)

匿名

2009-06-12 6:44 am

✔ 最佳答案

a): estimated (expected) population mean = 26weeks

b): 95% confidence intervals
26 - 1.96 x 6.2 / sqrt(50) < population mean < 2.6 + 1.96 x 6.2 / sqrt(50)
24.2815 < population mean < 27.7186

c): since 28weeks is outside the confidence intervals, it is an unreasonable guess

d): min. sample size = (2.5758 x 6.2 / 1.5)2 = 113.3535ppl < 114 ppl

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[匿名]

2009-06-13 4:11 am

thx u so much!!

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