Researchers have been studying p-loading in Jones Lake for many years. It is known that mean water clarity (using a Secchi disk) is normally distributed with a population standard deviation of o = 15.4 in. A random sample of 22 measurements was taken at various points on the lake with a sample mean of x = 57.8 in. The researchers want you to construct a 95% confidence interval for find; the mean water clarity. Confidence Level a (level of significance) 99% 1% 2.575 {a. b. 95% 59%6 1.96 90% 10% 1645