The article "Probabilistic Fatigue Evaluation of Riveted Railway Bridges" (J. of Bridge Eng., 2008: 237-244) suggested the exponential distribution with a mean value of 6 MPa as a model for the distribution of stress range in certain bridge connections.
Let's assume that this is, in fact, the true model. Then E(x) = 1/λ = 6 implies that λ = 0.1667.
Find:
a) the probability that the stress range is at most 10 MPa,
b) between 5 and 10 MPa,
c) the median (50th percentile).