The null and alternative hypothesis would be:
\[
\begin{array}{l}
H_{0}: \mu=H_{0}: \mu=H_{0}: p=0.15 \quad H_{0}: p=0.15 \quad H_{0}: \mu=H_{0}: p=0.15 \\
H_{1}: \mu \neq H_{1}: \mu< H_{1}: p< 0.15 H_{1}: p \neq 0.15 H_{1}: \mu> H_{1}: p> 0.15 \\
\end{array}
\]
The test is:
left-tailed right-tailed two-tailed os
Based on a sample of 115 men, $\frac{21}{115}$ of the men owned cats
The test statistic is: $z=$
(to 2 decimals)

Step 1 ：Define the null and alternative hypothesis as follows: \[H_{0}: p=0.15\] \[H_{1}: p \neq 0.15\]

Step 2 ：Based on a sample of 115 men, calculate the sample proportion (\(\hat{p}\)) of men who own cats as \(\frac{21}{115}\)

Step 3 ：Calculate the test statistic for a hypothesis test for a proportion using the formula: \[z = \frac{\hat{p} - p_0}{\sqrt{\frac{p_0(1-p_0)}{n}}}\] where \(\hat{p}\) is the sample proportion, \(p_0\) is the hypothesized population proportion, and \(n\) is the sample size

Step 4 ：Substitute the values into the formula: \(\hat{p} = \frac{21}{115}\), \(p_0 = 0.15\), and \(n = 115\)

Step 5 ：Calculate the test statistic to get \(z = 0.98\) to two decimal places

Step 6 ：Final Answer: The test statistic is \(\boxed{0.98}\)