A roadside assistance company gets millions of requests per year, with about a quarter of the requests in summer and a quarter in winter. Suppose that 12% of all of the summer requests and 15% of the winter
requests are for help with a lockout. A data analyst pulls separate random samples of 200 summer and winter
requests and will look at the difference (summer winter) between the proportion of requests for help with
a lockout in each sample.
What are the mean and standard deviation of the sampling distribution of the difference in sample
proportions?