A random sample of 500 adult residents of Maricopa Countyfound that 385 were in favor of increasing the highway speed limitto 75mph, while another sample of 400 adult residents of PimaCounty found that 267 were in favor of the increased speedlimit.
a) do these data indicate that there is a difference in thesupport for increasing the speed limit between residents of the twocounties? Use α = 0.05. What is the P-value forthis test?
b) construct a 95% confidence interval on the difference inthe two proportions. Provide a practical interpretation ofthis interval.
Please show formulas