Textbook costs Students taking a college introductory statistics class reported spending an average of $305 on textbooks that quarter with a standard deviation of $90. Here’s a rough sketch of a Normal density curve that fi tted the histogram well:

(a) Approximately what percent of the students spent between $215 and $395 on textbooks that quarter? Explain how you got this answer.

(b) One student spent $287 on textbooks. What was her standard score? What percent of the students spent less than she did on textbooks that quarter?