what is the standard deviation of this?

Question

what is the standard deviation of the number of dart throws I have to make until I get a bulls-eye (assuming my chances of making a bulls-eye on any throw is 0.739).

Answer 1

Number of throws until 1 success is a geometric distribution

p = 0.739

The variance is (1-p)/p²

so the standard deviation is [√ (1-p)] / p = 0.6913

the mean is 1/p = 1.353