we have,
the 90% confidence interval for population mean in this case is given by,
where is the upper point of the t- distribution with n observations.
in our case,
from the t-table we get,
Therefore the required CI is,
The Statistical assumptions that the sample comes from a normal distribution and the standard deviation of this normal distribution is unknown are not satisfied for the constructed confidence interval.
Exercise 5, Below are suminary statistics for n = 155 lead concentration measurements (in ppm) collected...