Your chemical facility consumes significant amounts of water. Six samples of 15 observations have been taken with the results shown here: Sample Mean Range 1 478,550 1,222 2 491,008 1,442 3 471,119 958 4 486,533 1,173 5 490,038 1,150 6 484,447 1,284 Calculate the lower and upper control limits for the mean.