Respuesta :
Using the t-distribution, it is found that:
a) Since the p-value of the test is 0.15 > 0.05, there is not significant evidence to conclude that the mean weight is below 325-mg, that is, that it meets specifications.
b) Any larger sample size does not ensure that regulations are met, it has to be significantly large such that t will be less than the critical value for the test.
At the null hypothesis, we test if the mean sodium content is of at least 325-mg, that is:
[tex]H_0: \mu \geq 325[/tex]
At the alternative hypothesis, we test if it is less than 325-mg, that is:
[tex]H_1: \mu < 325[/tex]
Item a:
We have the standard deviation for the sample, thus, the t-distribution is used. The test statistic is given by:
[tex]t = \frac{\overline{x} - \mu}{\frac{s}{\sqrt{n}}}[/tex]
The parameters are:
- [tex]\overline{x}[/tex] is the sample mean.
- [tex]\mu[/tex] is the value tested at the null hypothesis.
- s is the standard deviation of the sample.
- n is the sample size.
For this problem, the values of the parameters are: [tex]\overline{x} = 322, \mu = 325, s = 18, n = 40[/tex]
The value of the test statistic is:
[tex]t = \frac{\overline{x} - \mu}{\frac{s}{\sqrt{n}}}[/tex]
[tex]t = \frac{322 - 325}{\frac{18}{\sqrt{40}}}[/tex]
[tex]t = -1.05[/tex]
The p-value of the test is found using a left-tailed test, as we test if the mean is less than a value, with t = -1.05 and 40 - 1 = 39 df.
Using a t-distribution calculator, this p-value is of 0.15.
Since the p-value of the test is 0.15 > 0.05, there is not significant evidence to conclude that the mean weight is below 325-mg, that is, that it meets specifications.
Item b:
- Increasing the sample size decreases t which also decreases the p-value in a left-tailed test.
- However, the specifications are only met is t is lower than the critical value of t, hence, there has to be a significant increase in sample size.
Hence:
Any larger sample size does not ensure that regulations are met, it has to be significantly large such that t will be less than the critical value for the test.
A similar problem is given at https://brainly.com/question/25454581