Given:
μ = $3120, population mean
σ = $677, population standard deviation.
The population is normally distributed.
n = 20, sample size.
At the 95% confidence level, the confidence interval is
[tex]( \mu - 1.96\frac{\sigma}{ \sqrt{n} } ,\, \mu + 1.96\frac{\sigma}{ \sqrt{n} }) [/tex]
1.96(σ/√n) = 1.96(677/√20) = 296.71
Th confidence interval for the mean is
($2823.29, $3416.71)
Answer: ($2823.29, $3416.71)
