Question

Two AP Statistics students wanted to determine if there was a difference in time between the regular checkout lane at the local grocery store and the express “fast” checkout lane. To collect their data, they randomly selected 15 times during a week, went to the same store, and bought the same item. They flipped a coin to randomly select who would go through the regular lane and who would go through the express lane. They entered their randomly assigned lanes at the same time and recorded the time in seconds it took them to complete the transaction.

Express lane Time(seconds)	Regular Lane Time (seconds)
337	342
226	472
502	456
408	529
151	181
284	339
150	229
357	263
349	332
257	352
321	341
383	397
565	694
363	324
85	127

a.) Define µ_D.

µ_D = _______________________________________

b.) Why does a paired t test make more sense for this problem than a 2 sample t interval?

c.) Check conditions.

d.) Calculate a 90% confidence interval for the true difference in checkout time between the regular checkout lane and the express checkout lane at the local grocery store.

e.) Interpret your results.

d.) Is there evidence that there is a time difference between the regular checkout lane and express checkout lane at the local grocery store? Justify your answer.

Answer 1