 Hi Pam, I'm looking over your last two quizzes and this is the one five point one five point three. The first question that you had a partial miss on was this question about a survey and you got two parts of it right so I'm thinking you understand. I don't really know off the top of my head how you got point three three seven two for an answer. So for a second I've got this, ignore that for right now, the spreadsheet that I built and I think I shared it with the class or one like it and all you had to do for these normal probability problems is input the mean and standard deviation for your population. And one thing I wouldn't mention in some problems it's not clear if you're talking about a population or sample and in this case they say they had a survey of men and then you took a participant randomly from that so you had to kind of switch your thinking around and we're going to use this group of people that were surveyed as a population for the purposes of calculating the, of standardizing the values there. You put in the mean of that little group and standard deviation and then I put in the two values that the problem was asking about a lower value of 66 and an upper value of 71 and this spreadsheet calculates the Z values using the standardized function and then using this the norm distribution function we can calculate the area under the curve to the left of these values of Z. The one you missed should have been .2420 and again I don't know what you've keyed in wrong I'm guessing maybe you just keyed in a wrong number because you got the other two values correctly the value of less than 71 and the probability or the area under the curve between 66 and 71 is just the difference of these two values and I use the absolute formula in case you're dealing with negative numbers there but that is the probability of getting between 66 and 71 which is also the area and then the final one the probability of greater than 71 is just one minus the probability of less than or equal to 71 so you did that one pretty well. On this next problem you missed I think it just was the logic and perhaps you would do better if you could take the time to sketch the normal curve and the tricky thing here is the way they write these these questions is the probability of Z being less than or to the left of minus .76 or Z being greater than .76 to the right of so you're in those two tails what you calculated is the area between point minus .76 and plus .76 let's look at that XL spreadsheet again I've just modified it a bit to allow me to put in just the the Z values we were given of minus .76 plus .76 and you can use the norm s norm dot s dot dis function when you just are given the Z value and I use that same equation there as you can see for the plus and that gives you the value less less than minus .76 and then from left infinity to plus .76 gives you those two values if you subtract those two values that gives you the area between them of .5527 and that's what you came up with and then but we need the tails and so we just subtract that from one one minus G14 one minus .5528 gives me .4473 on number nine I think you just made a typo you entered 2.2 2.2 instead of 2.02 so uh I'm giving you essentially all credit for that oh heck I'll keep it 0.99 about that because it's just a dumb dumb I think which I make all the time the last question question 10 let's look at it and again you you've got the it appears to be that you've got the the wrong part of the curve let me bring up the XL here here's that XL spreadsheet that I built again and I just put in the values of minus 1.61 and plus .85 this time they gave you the sketch and they show you you want the area between not the area in the tails and I think again the answer what should be the area between .7486 and not the area in the tails 2.514 and yeah see you you essentially gave them the area in the tails and I'm guessing that there's a just a little bit of difference in the technology you use to calculate that area 2.2653 is not that far different from .214 that I get which gives you the exact answer that they're they're looking for there so I hope this helps