Answer
P-value $\ltα$. Reject the null hypothesis.
There is enough evidence to conclude that there is a difference between calcium levels in rainwater of Lincoln County and Clarendon County.
Work Step by Step
$H_0: M_{Lincoln}=M_{Clarendon}$ versus $H_1: M_{Lincoln}\ne M_{Clarendon}$
In MINITAB, enter the Lincoln County values in C1 and the Clarendon County values in C2.
Select Stat -> Nonparametrics -> Mann-Whitney
In "First Sample" enter C1 and in "Second Sample" enter C2. In "Confidence Level" enter 95. In "Alternative" select "not equal".
P-value $=0.001\ltα=0.05$
