The null hypothesis h0 is that the mean customer rating is...

The null hypothesis H0 is that the mean customer rating is equal to 75, and the alternative hypothesis H1 is that the mean customer rating is not equal to 75. The test statistic has a normal distribution and the value is given by (x - u) / (o / √n). Based on the test performed, there is enough evidence to support the claim that the mean customer rating is not equal to 75 at the 0.10 level of significance.

Transcript

00:01 So in this question first, we need to write what are the hypotheses.

00:05 So in the new hypothesis, we always have the equal sign.

00:09 And in the other one, we need to put what they want to check.

00:12 In this case, they want to check if the mean is different than the value 80.

00:20 So you already have this here, and because this is not the equal sign, this is in the alternative, then the new hypothesis will be the opposite of this sign.

00:29 So when we have the different sign, the opposite is the equal, when we have the greater, the opposite is less or equal.

00:36 When we have the less, the opposite is greater or equal.

00:40 So these will be the possible values that we can put in the new hypothesis, and these will always be the possible values that we can put in the alternative.

00:49 So as you can see, we always have the equal sign here, together with the less, together with the greater, or sometimes alone.

00:58 So in this case will be only the ecosine with the same value.

01:03 And because we are working with means, we should put the population parameter that represents the mean, not the sample parameter, or sample value, which is the x bar.

01:14 So this is the hypothesis in item a.

01:17 Then in item b we need to find the test statistics.

01:20 So basically we just need to apply the formula.

01:23 So the task statistic here, using the formula, is given by the value of the simple mean minus the value that we are testing, mill here, divided by the standard deviation that they gave us, divided by the square root of the sample size.

01:43 So this he will give us minus 1594.

01:46 Now that we have this information, we can go to the next step...

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