Assume that the service time for a customer at a bank is exponentially distributed with mean service time 2 minutes. Let X be the total service time for 10 customers. Estimate the probability that X > 22 minutes.
http://www.r-tutor.com/elementary-statistics/probability-distributions/exponential-distribution
set.seed(1)
m = 2 #mean = 2 for one customer
#for probablity that X < 22
p = pexp(22, rate=1/(m*10))
paste("The probablity that X > 22:", (1-p))## [1] "The probablity that X > 22: 0.332871083698079"