Die bestuurder van ʼn supermark bestudeer die hoeveelheid tyd wat nodig is vir ʼn klant om deur ʼn kassier gehelp te word. Hy bepaal dat die tyd wat klante by die betaalpunte spandeer eksponensiaal verdeel is met ʼn gemiddelde van ses minute. Die proporsie van klante wat meer as tien minute benodig om te betaal, is / The manager of a supermarket tracked the amount of time needed for customers to be served by the cashier. He determined that the checkout times are exponentially distributed with a mean of six minutes. The proportion of customers who require more than ten minutes to check out, is