Aiden bought some noteboks and book covers for the upcoming school year. he bought a total of 13 items. each notebook costs $1.37,and each book cover costs $1.08. he spent total of $16.36..how many notebooks and how many book covers did he buy?

The perimeter of a rhombus with a side of 6 is 24

(! ) three cylinders have a height of 8 cm. cylinder 1 has a radius of 1 cm. cylinder 2 has a radius of 2 cm. cylinder 3 has a radius of 3 cm. find the volume of each cylinder

The distribution of the amount of money spent by students for textbooks in a semester is approximately normal in shape with a mean of $235 and a standard deviation of $20. according to the standard deviation rule, how much did almost all (99.7%) of the students spend on textbooks in a semester?