00:01
Here we are told that a previous study showed that 64 % of supermarket shoppers believe supermarket brands to be as good as national name brands.
00:11
So that's a claim that the proportion.
00:14
And for part a, we are asked to develop hypotheses used to test this claim.
00:24
So the null hypothesis can be that the claim is true, that the population proportion is 0 .64.
00:34
And we want to test whether the proportion is different from 64%.
00:38
So the alternative hypothesis is that the population proportion is not 0 .64.
00:49
And then for part b, we consider a random sample of 100 shoppers, and of these, 52 felt that the supermarket brands were as good as the national brands.
01:06
And so based on this, we are asked for the p value.
01:10
So the first step is to calculate a test statistic.
01:16
This is given by the sample proportion, minus the null -hypothesized.
01:21
Proportion over the square root of the null proportion times 1 minus the null proportion over the sample size.
01:34
So the sample proportion, it's 52 over 100, or 0 .52, and this comes out to minus 2 .5 approximately.
02:08
So the next step is to calculate the p value associated with this test statistic.
02:15
We look at the alternative hypothesis.
02:17
It's a not equals to hypothesis, which means that this is a two -tailed test, and therefore the p value is equal to the probability of getting a number of the probability.
02:24
A test statistic at least as extreme as the one that we got in either the negative or positive directions.
02:45
Let's calculate this using excel...