Answer
$μ=0.11~mg/L$ lies inside the confidence interval: null hypothesis is not rejected.
There is not enough evidence to conclude that the calcium concentrations have changed since 1990.
Work Step by Step
$H_0: μ=0.11$ versus $H_1: μ\ne0.11$
Enter the data from Problem 23 in C1
Select Stat -> Basic Statistics -> 1-Sample t
Select "One or more samples, each in a column". In the box above enter C1
Click Options and enter the level of confidence 99%.
$Lower~Bound=0.0677$
$Upper~Bound=0.2459$
Since $0.0677\lt μ\lt0.2459$, we do not reject the null hypothesis.
