code class="asciimath">Consider the exponential distribution f(t) = ((1)/(\tau ) )e -(t)/(\tau ) (f(t) = 0 for t < 0). (a) Prove that the parameter \tau is the mean value of t, i.e. \tau = t ̄. (b) Prove that \tau is also the standard deviation, \sigma t = \tau . (c) Find the probability that any one value would fall in the range t ̄\pm \sigma t.