00:01
So we have 180 seats, so any time we have more than 180 it's a no -show.
00:05
So if x is the number who show and we have 185 seats, that means for this first part, the mean of x is going to be that 185 times point, this is no -show, so this is showing up as .95, and 185 times .95 is 175 .75, and i'm just going to store that as x.
00:44
And then we need the standard deviation, and i'll do that in blue, and the standard deviation is going to be that square root of that 185 times .95 times .05, and i'll store that also, times .05, the previous answer, and then we'll square root it, and that standard deviation is 2 .964, but again, i'm going to store that value in my calculator, and so i'm going to store it as a.
01:19
Now we want to find what the likelihood is of overbooking, and that means that x is greater than or equal to 180, greater than 181, so we convert that to a z value, 181 minus the mean of 175 .75, sorry about that, and then divided by that standard deviation, which is that 2 .964, and again, this is an approximation, and so we have 181 minus that value of the mean divided by that standard deviation, which i stored as alpha a, and we get that z value is approximately 1 .77, and then the area above that, looking that up on the normal distribution table, i'm actually going to look up the area below negative 1 .77, 0, 1, 2, 3, 4, 5, 6, 7, .0384, so approximately a 4 % chance of overbooking.
02:30
Now, if we have 200, we want to find the likelihood of an empty seat.
02:33
Well, so that's going to change our mean, so an empty seat, we're going to have the mean be 200 times the .95, and i'm still going to have x be the number that show up, so we have 200 times .95.
02:53
We would expect 190 people to show up, and the standard deviation will be that value times .05, and then square rooted, so i get that standard deviation is 3 .082, and again, i'm going to store that as alpha a...