00:01
For this problem, we have a sample size of n equals 120.
00:06
We know that the population proportion of recent college graduates in business who are women is 40%, 0 .4.
00:12
So we can model our distribution of sample proportions as a normal distribution, with a mean value equal to the population proportion, 0 .4, and a standard deviation given by the square root of the population proportion times 1 minus the population proportion, divided by the sample size, n.
00:29
So calculating that out, we'll have that the standard deviation is 0 .4 times 0 .6 divided by 120.
00:36
So that's 0 .045, roughly.
00:42
Now, the probability of the sample mean, or sample of proportion, being between 35%, which 0 .35, and 45%, positive 0 .45, we can find by taking the proportion of the standard normal distribution to the left of the z score corresponding to the upper bound.
01:01
So we do 0 .4...
01:02
Wrong thing there.
01:05
We do 0 .45 minus 0 .4, divided by 0 .045.
01:11
That's the z score of 1 .11...