Question

Noise levels at 4 volcanoes were measured in decibels yielding the following data: 153,156,168,138 Construct the 99% confidence interval for the mean noise level at such locations. Assume the population is approximately normal. Step 1 of 4 : Calculate the sample mean for the given sample data. Round your answer to one decimal place.

Answer 1

153.8 dB

Explanation:

The mean required in the firat step is calculated by dividing the sum of individual records by their frequency

`Mean=\frac {sum \ x}{n}`

Where n is frequency

In this case, since we are provided with four different records, their their sum will be given by

Sum x= 153+156+168+138=615 dB

Therefore, the mean will be

`Mean=\frac {615\ dB}{4}=153.75`

Rounding off to 1 decimal point, then the mean is approximately 153.8 dB