Why do we use lambda = 2 here? Why not use lambda = 10, since that is the average over the whole period?

A flash light emits flash bursts at random times, at an average rate of 2 bursts per second.

1. (a)Assume that the time T between any two light bursts is an exponential random variable. What is the probability that no burst is emitted in the next five seconds?

Solution: Using time units of seconds we have T Exp(2). Therefore, we have

P({T > 5}) = e25 = e10 .454 104.