Question

g In an experiment, 37 randomly selected drivers drove from Pontiac to Detroit at random times. The travel time for these drivers was 39.0 minutes on average with a standard deviation of 4.8 minutes. Calculate and interpret a 99.9% confidence interval for the mean travel time for all possible drivers traveling from Pontiac to Detroit.

Answer 1

CI = ( 36,6 ; 41,4 )

Explanation:

CI = 99,9 % α = 0,1 % α = 0,001

We find z scre for α = 0,001 in z -table

z(s) = - 3,08

CI = μ₀ ± MOE where μ₀ = 39 min and MOE = z(s) * σ/√n

CI = 39 ± 3,08 * 4,8 / √37

CI = 39 ± 2,4315

CI = ( 36,6 ; 41,4 )