Question

A random sample of n₁ = 14 winter days in Denver gave a sample mean pollution index x₁ = 43. Previous studies show that σ₁ = 21. For Englewood (a suburb of Denver), a random sample of n₂ = 16 winter days gave a sample mean pollution index of x₂ = 35. Previous studies show that σ₂ = 13. Assume the pollution index is normally distributed in both Englewood and Denver.

What is the value of the sample test statistic? Compute the corresponding z or t value as appropriate. (Test the difference μ₁ − μ₂. Round your answer to two decimal places.)


(iii) Find (or estimate) the P-value. (Round your answer to four decimal places.)

(b) Find a 99% confidence interval for

μ₁ − μ₂.

(Round your answers to two decimal places.)

lower limit
upper limit

Answer 1

The statistical software output for this problem is :

Test statistics = 1.23

P-value = 0.2174

Lower limit = -8.71

Upper limit = 24.71