Suppose a researcher is interested in understanding the variation in price of store brand milk. A random sample of 36 grocery stores selected from a population and the mean price of store brand milk is calculated. The sample mean is $3.13 with a population standard deviation of $0.23. Construct a 95% confidence interval to estimate the population mean. (a) 3.03 to 3.23 (b) 3.12 to 3.14 () 3.05 to 3.21 (d) 2.90 to 3.36