Answer:
The Sample size is 1918.89035
Step-by-step explanation:
Consider the provided information.
It is given that 14 out of 105 samples failed.
Therefore p = 14/105 = 0.13 3... and q=1-0.133=0.867
Samples would be needed to create a 99 percent confidence interval.
Subtract the confidence level from 1, then divide by two.
By standard normal table z=2.5758≈2.58
Calculate the sample size as:
Where, e is the margin of error,
Substitute the respective values.
Hence, the Sample size is 1918.89035
Answer:
Explained below.
Step-by-step explanation:
(1)
The hypothesis can be defined as follows:
<em>H</em>₀: The Speedy Oil Change will change the oil in customers’ cars in more than 30 minutes on average, i.e. <em>μ</em> > 30.
<em>H</em>ₐ: The Speedy Oil Change will change the oil in customers’ cars in less than 30 minutes on average, i.e. <em>μ</em> ≤ 30.
(2)
Use Excel to compute the sample mean and standard deviation as follows:
Compute the test statistic as follows:
The degrees of freedom is:
df = n - 1
= 36 - 1
= 35
Compute the p-value as follows:
(3)
The <em>p</em>-value = 0.0006 is very small.
The null hypothesis will be rejected at any of the commonly used significance level.
(4)
There is sufficient evidence to support the claim that the Speedy Oil Change will change the oil in customers’ cars in less than 30 minutes on average.
