ch.8 interval mean

Question

question 1

Karen wants to advertise how many chocolate chips are in each Big Chip cookie at her bakery. She randomly selects a sample of 31 cookies and finds that the number of chocolate chips per cookie in the sample has a mean of 8.7 and a standard deviation of 2.4. What is the 99% confidence interval for the number of chocolate chips per cookie for Big Chip cookies?

Enter your answers accurate to one decimal place (because the sample statistics are reported accurate to one decimal place).Incorrect_____ <  < _____

Answer 1

CI = sample mean +/- margin of error (MOE)

where MOE = critical t * standard deviation/sqrt(sample size)

critical t* is for alpha/2 = 0.005 and 30 degrees of freedom = 2.750

you are given other values in the equation

CI will be sample mean - MOE < u < sample mean + MOE