The following table gives the grouped data on the ounces of milk dispensed by a machine into 1 gallon jugs for a sample of 250 jugs of milk selected from a day’s production. Note that 1 gallon is equal to 128 ounces.
Ounces of Milk Number of Jugs
121 to less than 123......... 5
123 to less than 125......... 13
125 to less than 127......... 42
127 to less than 129......... 129
129 to less than 131......... 61
Find the mean, variance, and standard deviation.