Let$$s imagine your guess for the next waiting time was always just the length of the previous waiting time. If you always guessed the previous waiting time, how big would your error in guessing the waiting times be$,$ on average? $(4$ Points$)$

For example, since the first four waiting times are $79,54,74,$ and $62,$ the average difference between your guess and the actual time for just the second, third, and fourth eruptions would be

$.$