. Jethro's BBQ Food Truck. Jethro's BBQ is a local chain of restaurants located at central Iowa. Bruce, the owner of the restaurant located at Ames, is thinking about expanding his business using a food truck that would be located during weekdays at the ISU campus. One important aspect for the planning of such project is to determine what would be a reasonable price range for the food. The prices need to be appealing and affordable for college students and at the same time be high enough so the food truck ends up being profitable. The first goal Bruce sets is to determine how much money on average ISU students spend buying lunch during weekdays. Bruce spent a morning asking students all around campus how much money they spend on buying lunch during weekdays. He got an answer from 87 students yielding to an average daily spend of $10.56. Bruce found out that five years ago ISU conducted a very complete study on students spending, and the standard deviation back then for daily spend on lunch was $1.78. Bruce assumed the standard deviation has not changed.

(d) Similarly, now calculate a 85% confidence interval for the unknown population mean, .

i. Find the positive z-score (z ) for the corresponding confidence level. (Round your answer to 2 decimal places).

ii. Find the lower and the upper bound of the confidence interval. (Round your answer to 2 decimal places).

iii. Which of the following represents a correct interpretation of the 85% confidence interval for in the context of the problem? Select ALL correct answers.

A. If we take 100 samples and calculate 85% confidence intervals for each, we expect 85 out of the 100 intervals to contain the average amount of money ISU students spend buying lunch during weekdays.

B. We are 85% confident that the sample mean of how much the 87 ISU students sampled spend buying lunch during weekdays ($10.56) falls between $10.29 and $10.83.

C. There is a 85% chance the sample mean of how much the 87 ISU students sampled spend buying lunch during weekdays ($10.56) falls between $10.29 and $10.83.

D. We are 85% confident that the average amount of money ISU students spend buying lunch during weekdays falls between $10.29 and $10.83.