In a particular municipality, it is believed that 25 percent of homes are not properly insulated. In order to test H0 :p=.25 vs. HA :p≠.25 (where p is the population proportion of homes that are not properly insulated) a random sample of 300 homes was selected. In the sample, it was found that 93 homes were not properly insulated.
If the null hypothesis is true, then the z-score for the sample proportion is: