Answer
P-value $=0.0391\ltα$. Reject the null hypothesis.
There is enough evidence to conclude that there is a difference in the pH of rain in Chicago and Houston.
Work Step by Step
$H_0:~µ_{Chicago}=µ_{Houston}$ versus $µ_{Chicago}\neµ_{Houston}$
In MINITAB, enter the Texas values in C1 and the Illinois values in C2.
Select Stat -> Basic Statistics -> 2-Sample t
Select "Each sample is in its own column"
In Sample 1 enter C1 and in Sample 2 enter C2
Click in Options. Enter 95 in Confidence level, 0 in Hypothesized difference. In "Alternative hypothesis" select "Difference $\ne$ hypothesized difference". Click OK.
Click OK.
