a. P (hit on second shot) = 0.28 + 0.24 = 0.52
b. P (miss on first | hit on second) = (0.24)/(0.52) = 6/13 = 0.46.- Let p 1 be the true proportion who planned to vote for Buffy before her remarks. Let p 2 be the true
proportion who plan to vote for Buffy after her remarks.We want to use a 2-proportion z test for this situation. The problem tells us that the samples are
random samples.Now, 72(0.83), 72(1 – 0.83), 80(0.70), and 80(1 – 0.70) are all greater than 5, so the conditions for
the test are present.Because P is very low, we reject the null. We have reason to believe that the level of support for
Buffy has declined since her “unfortunate” remarks.
The data are paired, so we will use a matched pairs test.
Let μ (^) d = the true mean difference between Twin A and Twin B for identical twins reared apart.
We want to use a one-sample t -test for this situation. We need the difference scores:
A dotplot of the difference scores shows no significant departures from normality: