Teachers in United States high schools teach an average (arithmetic mean) of 80 hours per month, with a variance of 100. What numbers of monthly teaching hours is exactly two standard deviations away from the mean?

For the rule of 78, for a 12-month period, the last term in the sequence is 12 and the series sums to 78. for an 10 month period, the last term is and the series sum is . for a 15 month period, the last term is and the series sum is . for a 20 month period, the last term is and the series sum is

Terri makes a quilt using three sizes of fabric squares the side lenght of each fabric square is the square root of the area

Sasha drank 8 bottles of water everyday for a week. how many bottles of water did she drink in total?