00:01
So this problem is a binomial distribution problem and it tells us that a simple random sample of 75 is obtained from a population with a proportion with a specified characteristic of p equals 0 .8.
00:14
Let's start with part a, which asks us to describe the sampling distribution of p hat.
00:19
Before we do that, we'll have to define our three important variables of n, p, and q.
00:25
So it gives us n, which is 75, that's the sample size.
00:29
It gives us p as well, which is 0 .8.
00:33
And then q is simply 1 minus p, so 1 minus 0 .8 is just 0 .2.
00:39
Now with these variables, we're ready to find our mean and standard deviation, as i have the equations for all the screen.
00:46
So starting with the mean, the mean is equal to n times p, so 75 times 0 .8, which comes out to 60.
00:54
Standard deviation is equal to the square root of n times p, so that's the square root of 7.
01:00
Or excuse me the square root of n times p times q so it's a square root of 75 times 0 .8 times 0 .2 and this is equal to 3 .464.
01:14
So our since our mean is greater than 5 that means that we are dealing with a normal distribution, mean of 60 and a standard deviation of 3 .464.
01:31
Now we'll move on to part b which asks us to define the the probability of obtaining 63 or more individuals with this characteristic.
01:41
So what we're finding is the probability of x being greater than or equal to 63 since it asks for 63 or more.
01:49
Now because of this equal sign here we'll have to do a continuity correction for 63, meaning we'll have to subtract 0 .5.
01:56
So what we're really finding is the probability of x being greater than 62 .5...