Question

The following are airborne times (in minutes) for 10 randomly selected flights from San Francisco to Washington Dulles airport. 269 255 267 285 274 275 266 258 271 281

(a) Compute a 90% confidence interval for the mean airborne time for flights from San Francisco to Washington Dulles. (Round your answers to three decimal places.)

(b) Give an interpretation of the 90% confidence level associated with the interval estimate in part (a).

a) If we were to take a large number of random samples of size 10, 10% of the resulting confidence intervals would contain the true mean airborne time.

b) If we were to take a large number of random samples of size 90, 10% of the resulting confidence intervals would contain the true mean airborne time.

c)If we were to take a 10 random samples of size 10, 10% of the resulting confidence intervals would contain the true mean airborne time.

d) If we were to take a large number of random samples of size 10, 90% of the resulting confidence intervals would contain the true mean airborne time.

If a flight from San Francisco to Washington Dulles is scheduled to depart at 10 A.M., what would you recommend for the published arrival time? Explain.

a) We would recommend 2:50 P.M., assuming normality and that this sample is representative of the population. We can assume that approximately 95% of flights will arrive after this time.

b)We would recommend 4:50 P.M., assuming normality and that this sample is representative of the population. We can assume that approximately 5% of flights will arrive after this time.  

c) We would recommend 1:50 P.M., assuming normality and that this sample is representative of the population. We can assume that approximately 5% of flights will arrive after this time.

d)We would recommend 2:50 P.M., assuming normality and that this sample is representative of the population. We can assume that approximately 5% of flights will arrive after this time.

e)We would recommend 3:50 P.M., assuming normality and that this sample is representative of the population. We can assume that approximately 5% of flights will arrive after this time.

Answer 1

From the given data ,

Sample mean =

Sample standard deviation = s = 9.3268

n = 10

a ) Therefore , the 90% confidence interval for the mean is ,

b ) Interpretation :

d) If we were to take a large number of random samples of size 10, 90% of the resulting confidence intervals would contain the true mean airborne time.