Suppose, you are running an experiment that has two outcomes, namely 'success' and 'failure'. You intially don't know the probability of success in a single experiment. But you know that, if you...

Suppose, you are running an experiment that has two outcomes, namely 'success' and 'failure'. You intially don't know the probability of success in a single experiment. But you know that, if you continue to run the experiment several times, the expected number of experiment required for the first success is 25. What is the variance of the number of experiments required for the first success?