Solution
= Solution
As $r_0\to+\infty$, the exponential factor tends to zero, so \b[$P(r>r_0)\to0$]. Requiring an arbitrarily large amount of remaining time must have vanishing <probability> for this finite-mean distribution.
= Solution
As $r_0\to+\infty$, the exponential factor tends to zero, so \b[$P(r>r_0)\to0$]. Requiring an arbitrarily large amount of remaining time must have vanishing <probability> for this finite-mean distribution.