In a problem similar to that in Question 35 the probability of success at the first attempt is 0.2 but the probability of failure at each subsequent attempt (if needed) is half of that for the previous attempt. Find the mean number of attempts needed to achieve the first success.

Data from Question 35

The distribution of the number X of independent attempts needed to achieve the first success when the probability of success is 0.2 at each attempt is given by

Find the mean, the median and the standard deviation for this distribution.

Transcribed Image Text:

k-1 P(X= k) = (0.2)(0.8) (k = 1, 2, 3, ...)