Question

Noise levels at 5 airports were measured in decibels yielding the following data:

154,104,155,124,116

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

Step 3 of 4: Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places.

step 4 of 4:Construct the 80% confidence interval. Round your answer to one decimal place.

Answer 1

Step 3 )

df = n - 1 = 5 - 1 = 4

From T table,

t critical value at 0.20 significance level with 4 df = 1.533

Step 4)

From Sample data,

= 130.6 , S = 22.9521

80% confidence interval for is

- t * S / sqrt(n) < < + t * S / sqrt(n)

130.6 - 1.533 * 22.9521 / sqrt(5) < < 130.6 + 1.533 * 22.9521 / sqrt(5)

114.9 < < 146.3

80% CI is ( 114.9 , 146.3 )