When we first learn arithmetic, we focus on working with whole numbers. Then, we extend our understanding of fractions and negative numbers. In algebra, we transfer these same skills to expressions involving variables. What elementary skills have you used so far in this course, and how have you extended them?

The weekly amount spent by a company for travel has an approximately normal distribution with mean = $550 and standard deviation = $40. a) what is the probability that the actual weekly expense will exceed $570 for more than 20 weeks during the next year? (note: one year = 52 weeks) b) what is the probability that actual weekly expenses exceed $580 for 10 or more, but 16 or fewer weeks during the next year?