Question

A trade magazine routinely checks the​ drive-through service times of​ fast-food restaurants. An 80​% confidence interval that results from examining 613 customers in one​ fast-food chain drive-through has a lower bound of 178.2 seconds and an upper bound of 181.4 seconds. What does this​ mean?

There is an 80% probability that the mean drive-through service time is between ___ and ___ seconds.

Answer 1

Solution :

lower bound = 178.2

upper bound = 181.4

  = (Lower confidence interval + Upper confidence interval ) / 2

Sample mean = = (178.2 + 181.4) / 2

Sample mean = = 179.8

There is an 80% probability that the mean drive-through service time is between 178.2 and 181.4 seconds.