A purveyor of designer maternity wear sells dresses and pants priced around $150 each for an average total sale of $1,100. The total sale has a normal distribution with a standard deviation of $450. Complete parts a through c below. 

a. Calculate the probability that a randomly selected customer will have a total sale of more than $1,700. The probability is 0.1314. (Round to four decimal places as needed.) 

b. Compute the probability that the total sale will be within plus or minus2 standard deviations of the mean total sales.