> mean(BWT)
[1] 122.22
> sd(BWT)
[1] 15.37197
Note: Since the population standard deviation $\sigma$ is unknown, use the sample standard deviation, $s$ (given
above), in its place.
a) [3] Using this information, construct a 95% confidence interval for the mean BWT.
b) [1] What is the margin of error from the interval you calculated above?
c) [2] Will a 90% confidence interval for the mean BWT be wider or narrower than the interval you
calculated in (a)? Why? You can answer the question either by calculating the 90% confidence
interval or looking at what changes in the formula with a 90% confidence level.
d) [2] Based on the information provided above, do the assumptions necessary for constructing the
confidence interval appear to be met?