Let Xi be the allowance the boy gets in the ith week. Find the expected calue, variance, and standard deviation of Xi.

Times for a surgical procedure are normally distributed. There are two methods. Method A has a mean of 31 minutes and a standard deviation of 2 minutes, while method B has a mean of 35 minutes and a standard deviation of 1.0 minutes. (a) Which procedure is preferred if the procedure must be completed within 30 minutes? O Method A O Method B O Either Method (b) Which procedure is preferred if the procedure must be completed within 38.0 minutes? O Either Method O Method A O Method B (c) Which procedure is preferred if the procedure must be completed within 37 minutes? O Method B O Either Method O Method A < Prev 19 of 19 Next to search 22 立

Suppose that water usages in American showers are normally distributed, with an average shower using 17.1 gallons, and a standard deviation of 3.5 gallons. Estimate the percentage of showers that used(a) between 6.6 and 27.6 gallons.__________%(b) more than 27.6 gallons.__________ %(c) less than 13.6 gallons. __________%(d) between 13.6 and 27.6 gallons. __________%   Answer the blanks.

Jeremiah earned a score of 530 on Exam A that had a mean of 450 and a standard deviation of 40. He is about to take Exam B that has a mean of 63 and a standard deviation of 20. How well must Jeremiah score on Exam B in order to do equivalently well as he did on Exam A? Assume that scores on each exam are normally distributed.