The number of candy pieces in a bag is calculated for a sample of 40 bags of a particular manufacture. Based on this data, the sample mean is 20.35 pieces. The population standard deviation is to be 3.6 (remember this is the unrealistic part, we would not really know this).

Which below is a 95% confidence interval for the mean number of pieces of candy per bag?

Note: 95% of all possible confidence intervals for a sample size of 30 will contain the population mean. Use 1.960 for a 95% CI and 2.576 for 99% CI.

a. (18.87, 22,12)

b. (20.33, 21.82)

c. (20.17,20.52)

d. (19.23,21.47 )