What’s the area of the triangle

According to the normal model, what percent of receivers would you expect to gain fewer yards than 2 standard deviations below the mean number of yards

Atheater wants to build movable steps that they can use to go on and off the stage. they want the steps to have enough space inside so they can also be used to store props. how much space is inside the steps?

What function has a range {yly< 5}? question on picture above^