Question

Describe in detail how you would construct a 95% confidence interval for a set of 30 data points whose mean is 20 and population standard deviation is 3.

Answer 1

n = 30, so we can say we have a large enough sample to use the normal distribution (z-table)
Write out the given values: sample mean, \[\bar{X} = 20\] and sample standard deviation, \[\sigma = 3\]
Recall that the general expression for a confidence interval with large enough sample and a known population standard deviation is given by
\[\bar{X} \pm Z_{\frac{\alpha}{2}} \frac{\sigma}{\sqrt{n}}\]
Now plug in your given values, where \[\alpha\] is 0.05 (5%). Find the value on the table, plug it in, and you're done!

Answer 2

thnx man yo helped alot