Karen wants to advertise how many chocolate chips are in each Big Chip cookie at her bakery. She randomly selects a sample of 33 cookies and finds that the number of chocolate chips per cookie in the sample has a mean of 15.9 and a standard deviation of 2.9. What is the 80% confidence interval for the number of chocolate chips per cookie for Big Chip cookies? a.) Which distribution table will be used to find the critical value and why?

• Z-table because the population standard deviation is unknown
• t-table because the population standard deviation is unknown
• Z-table because the population standard deviation is known
• t-table because the population standard deviation is known

b.) With 80% confidence, we can say the true population mean of chocolate chips per cookie in Big Chip cookies is between **** and ***.