Exponential Distribution Work station.

Initial data suggest that the times required for processing pieces at this station may be treated as having an exponential distribution with a mean of three hundred seconds.

a) If fifty pieces are processed, about how many of them take between two hundred forty and three hundred sixty seconds to process?

b) What is the probability that more than the mean number of pieces will be processed in a ten-minute period?

c) What is the median processing time at the station?

d) What proportion of processing times are within two standard deviations of the mean?