 Hi, this is Dr. Don. I have a problem on the difference in proportions, which is chapter 8, section 0.4 in the McClave text. In this problem, we're told that a COLA manufacturer had consumers take a blind taste test. And they were asked to decide which of two sodas they preferred. The manufacturer was interested in the factors that played a role and was interested to know if males preferred its brand more than females. Well, let's stop right there. Since we're told that we want to know if males prefer something more than females, that's a hint that this is categorical data. And if we have categorical data, then we will run a Z test for proportions. The problem goes on and says, using the test statistic given in the printout, compute the appropriate p-value. Well, they give you a lot of information there, and you can use this information to do the actual Z test for difference in proportions. But they give you a clue there, using the test statistic. We look down at the very bottom, and it gives us a Z value of 2.11825. That's our test statistic, or as some people call it, the standardized test statistic. And that's all we need to solve this problem. We're going to call up StatCrunch, and I'll show you how to do this very quickly. Okay, I have StatCrunch open, and all we need to do when we are given a Z statistic, a Z score, we can go into StatCalculatorsNormal, bring up our normal calculator, and again the default is the standard normal distribution, which is what we want. We need to read the problem there. He wants to know if males preferred the cola more than females. That tells us that the alternative cola manufacturer is interested in is a greater than. In the male sample, greater than the proportion in the female sample. So in our calculator, we go down here and we click the greater than symbol, which means we want a right-hand tail test. And all we need to do is put in that Z value, 2.11825, and click compute. And we get our answer. The probability of having a Z value greater than that 2.11825 is 0.0171. Pretty small. But that's all you have to do to get this answer. Hope this helps.