Answer:
The pvalue of the test is 0.177 > 0.02, which means that at α=0.02, you cannot reject the company's claim.
Step-by-step explanation:
A company that makes cola drinks states that the mean caffeine content per 12-ounce bottle of cola is 35 milligrams. You want to test this claim.
At the null hypothesis, you test that the mean caffeine content is of 35 milligrams, that is:
And at the alternate hypothesis, you test if the content is different from 35, so:
The test statistic is:
In which X is the sample mean, is the value tested at the null hypothesis,
is the standard deviation and n is the size of the sample.
35 is tested at the null hypothesis:
This means that
During your tests, you find that a random sample of thirty 12-ounce bottles of cola has a mean caffeine content of 36.8 milligrams. Assume the population is normally distributed and the population standard deviation is 7.3 milligrams.
This means that
Value of the test statistic:
Pvalue of the test and decision:
The pvalue of the test is the probability of the mean caffeine content differing from the mean by at least 36.8 - 35 = 1.8, which is P(|z| > 1.35), which is 2 multiplied by the pvalue of z = -1.35.
Looking at the z = -1.35 has a pvalue of 0.0885
2*0.0885 = 0.177
The pvalue of the test is 0.177 > 0.02, which means that at α=0.02, you cannot reject the company's claim.