00:01
For this problem, we are told that in a court case reviewed by the supreme court, the plaintiffs alleged that the method for selecting juries in a county in texas was biased against mexican americans.
00:09
For the period of time at issue, there were 181 ,535 persons eligible for jury duty, of whom 143 ,611 were mexican americans.
00:21
Of the 870 people selected for jury duty, 339 were mexican americans.
00:29
In part a, we are asked, what proportion of eligible jurors were mexican americans? and we are to denote this value by p.
00:36
Not.
00:37
So that would be, let's see here.
00:40
That would be 143 -611, divided by 181 -535.
00:46
So i'll get the numerical value here, round it.
00:49
So about 79%.
00:51
So p -0 is about 0 .79.
00:57
For part b, we're asked to let p be the probability that a randomly select juror is a mexican -american.
01:04
The null hypothesis to be tested is h -0, or is rather that p -0 equals p -not.
01:10
We're asked to find the value of p -hat, the sample proportion for this problem, to compute the z -statistic and estimate the p -value.
01:18
So, p -hat is going to be equal to, let's see here, 339, over 870, which gives us a result here of about approximately 0 .39.
01:39
Then our z score is going to be equal to p hat 0 .39 minus p .9, minus p .9, divided by the square root of p .0 .0 .79 times 1 minus p .0 over n.
01:58
And n was 870 .7 .000.
02:00
And n was 870.
02:00
So our z score, i'll just calculate this out here, 0 .39 minus 0 .79, divided by the square root of 0 .79 times 1 minus 0 .79 over 870.
02:16
So, wowza.
02:18
Our z score is negative, it's about negative 28 .97.
02:25
So we can reasonably estimate the p value as being approximately zero because of, how many standard deviations away, or essentially because of how large that z score is, p is very close to zero.
02:42
So we would reject the null hypothesis.
02:48
Then, for part c, whereas to reformulate the problem is a two -sample problem, where we wish to compare the proportion of mexican -americans among those selected as jurors with the proportion of mexican -american, pardon me, mexican -americans among those not selected as jurors...