A library has 142 cds on its shelves. there are 11 shelves that have 8 cds on each shelf. the rest of the shelves have 6 cds on each shelf. how many shelves gave 6 cds

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?