Question

The Customs and Border Protection (CBP) agency claims that its officers process arriving international passengers in an average time of 20 minutes at Washington Dulles International Airport (IAD) even though there has been a staffing reduction due to budget cuts. Historical data indicates that the population standard deviation of passenger processing time at IAD is 5 minutes. A congressional committee wants to check the CBP claim. A sample of 60 arriving international passengers yielded an average processing time of 22 minutes.

a. What is the population for which inferencing is being done in this setting?

b. Construct a 93% confidence interval for the average time taken by CBP to process arriving international passengers at IAD

c. Based on your answer in (b) should the congressional committee believe the CBP claim? Justify briefly.

d. How many arriving should be sampled in order to estimate the average processing time with a margin of error of 1 minute at 97% confidence?

Answer 1