Confidence Intervals for Population Means

Question

Assume that a sample is used to estimate a population mean μμ. Find the 80% confidence interval for a sample of size 544 with a mean of 20.6 and a standard deviation of 20.8. Enter your answer as a tri-linear inequality accurate to one decimal place (because the sample statistics are reported accurate to one decimal place).

________< μ <_________

Answer 1

The confidence interval is μ ± (z(.10 in the tail))*(σ/sqrt(n))

From the standard normal z chart z = 1.28 for .1 in the RH tail.

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