The producer of a certain bottling equipment claims that the variance of all its filled bottles is .027 or less. A sample of 30 bottles showed a standard deviation of .2. The p-value for the test is _____.

a. .025
b. between .025 and .05
c. .05
d. between .05 and .01

Respuesta :

Answer:

[tex]p_v = P(\chi^2_{29}>42.963)=1-0.954=0.0459[/tex]

b. between .025 and .05

Step-by-step explanation:

Previous concepts and notation

The chi-square test is used to check if the standard deviation of a population is equal to a specified value. We can conduct the test "two-sided test or a one-sided test".

[tex]\bar X [/tex] represent the sample mean

n = 30 sample size

s= 0.2 represent the sample deviation

[tex]\sigma_o =\sqrt{0.027}=0.164[/tex] the value that we want to test

[tex]p_v [/tex] represent the p value for the test

t represent the statistic

[tex]\alpha=[/tex] significance level

State the null and alternative hypothesis

On this case we want to check if the population standard deviation is less than 0.027, so the system of hypothesis are:

H0: [tex]\sigma \leq 0.027[/tex]

H1: [tex]\sigma >0.027[/tex]

In order to check the hypothesis we need to calculate the statistic given by the following formula:

[tex] t=(n-1) [\frac{s}{\sigma_o}]^2 [/tex]

This statistic have a Chi Square distribution distribution with n-1 degrees of freedom.

What is the value of your test statistic?

Now we have everything to replace into the formula for the statistic and we got:

[tex] t=(30-1) [\frac{0.2}{0.164}]^2 =42.963[/tex]

What is the approximate p-value of the test?

The degrees of freedom are given by:

[tex] df=n-1= 30-1=29[/tex]

For this case since we have a right tailed test the p value is given by:

[tex]p_v = P(\chi^2_{29}>42.963)=1-0.954=0.0459[/tex]

And the best option would be:

b. between .025 and .05