Question

Noise levels at 66 manufacturing plants were measured in decibels yielding the following data:

147,144,146,127,154,140147,144,146,127,154,140

Construct the 80%80% confidence interval for the mean noise level at such locations. Assume the population is approximately normal.

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Step 4 of 4:

Construct the 80%80% confidence interval. Round your answer to one decimal place.

Answer 1

$80\%~CI~for~mean:\\\\ \left(\bar{x}-t_{0.10,n-1}\times \frac{s}{\sqrt{n}}, ~~\bar{x}+t_{0.10,n-1}\times \frac{s}{\sqrt{n}}\right )=(139.6,~146.4)\\\\ where,~n=sample~size=12,~\bar{x}=sample~mean=143,\\ s=sample~sd=8.655,~t_{0.10,n-1}=1.3634$