Respuesta :
Answer:
The pvalue of the test is 0.0007 < 0.01, which means that we reject the null hypothesis and accept the alternate hypothesis that the percentage of defective items produced by this machine is greater than 5%.
Step-by-step explanation:
A machine, when working properly, produces 5% or less defective items.
This means that the null hypothesis is:
[tex]H_0: p \leq 0.05[/tex]
Test if the percentage of defective items produced by this machine is greater than 5%.
This means that the alternate hypothesis is:
[tex]H_a: p > 0.05[/tex]
The test statistic is:
[tex]z = \frac{X - \mu}{\frac{\sigma}{\sqrt{n}}}[/tex]
In which X is the sample mean, [tex]\mu[/tex] is the value tested at the null hypothesis, [tex]\sigma[/tex] is the standard deviation and n is the size of the sample.
0.05 is tested at the null hypothesis:
This means that [tex]\mu = 0.05, \sigma = \sqrt{0.05*0.95}[/tex]
A random sample of 300 items taken from the production line contained 27 defective items.
This means that [tex]n = 300, X = \frac{27}{300} = 0.09[/tex]
Value of the test statistic:
[tex]z = \frac{X - \mu}{\frac{\sigma}{\sqrt{n}}}[/tex]
[tex]z = \frac{0.09 - 0.05}{\frac{\sqrt{0.05*0.95}}{\sqrt{300}}}[/tex]
[tex]z = 3.18[/tex]
Pvalue of the test:
Testing if the mean is greater than a value, which means that the pvalue of the test is 1 subtracted by the pvalue of Z = 3.18, which is the probability of a finding a sample proportion of 0.09 or higher.
Looking at the Z-table, Z = 3.18 has a pvalue of 0.9993
1 - 0.9993 = 0.0007
The pvalue of the test is 0.0007 < 0.01, which means that we reject the null hypothesis and accept the alternate hypothesis that the percentage of defective items produced by this machine is greater than 5%.
