Find the value of x. if necessary round your answer to the nearest tenth. the figure is not drawn to scale
1 answer:
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Answer:
The 80% confidence interval for the mean repair cost for the washers is between $34.60 and $70.66.
Step-by-step explanation:
We have the standard deviation for the sample, which means that the t-distribution is used to solve this question.
The first step to solve this problem is finding how many degrees of freedom, we have. This is the sample size subtracted by 1. So
df = 4 - 1 = 3
80% confidence interval
Now, we have to find a value of T, which is found looking at the t table, with 3 degrees of freedom(y-axis) and a confidence level of . So we have T = 1.638
The margin of error is:
In which s is the standard deviation of the sample and n is the size of the sample.
The lower end of the interval is the sample mean subtracted by M. So it is 52.63 - 18.03 = $34.60
The upper end of the interval is the sample mean added to M. So it is 52.63 + 18.03 = $70.66.
The 80% confidence interval for the mean repair cost for the washers is between $34.60 and $70.66.