Another way to write (6+7)x

3.17 scores on stats final. below are final exam scores of 20 introductory statistics students. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 57, 66, 69, 71, 72, 73, 74, 77, 78, 78, 79, 79, 81, 81, 82, 83, 83, 88, 89, 94 (a) the mean score is 77.7 points. with a standard deviation of 8.44 points. use this information to determine if the scores approximately follow the 68-95-99.7% rule. (b) do these data appear to follow a normal distribution? explain your reasoning using the graphs provided below.

Can someone plz me with 11,12,13 plz show work

Mary and roberto bought identical backpacks at different stores. mary's backpack originally cost $65 and was discounted 25%. roberto's backpack originally cost $75 and was on sale for 30% off on the original price. which backpack was the better buy?