The manufacturer of a particular brand of crackers claims that the mean weight for the boxes of crackers is 388 grams.To test this claim, a group of students carefully weighed the contents of 100 boxes, and found a mean weight of 380 grams with standard deviation 30 grams. We want to use this information to decide if the mean weight is less than 388 grams.

a) At significance level 0.05, do you reject the null hypothesis?

b) As a result of this hypothesis test, do you conclude that mean weight for the population of all of these cracker boxes is less than 388 grams?

c) Construct a 95% confidence interval for the mean weight of these bags of chips.

Please round your answers to two decimal places.

lower limit =

upper limit =