Assume that you perform and experiment where the outcomes occur according to a Poisson Process with rate 4 per minute, and that the experiment is complete once you observe 250 outcomes. Calculate the mean time and variance time of the experiment.

for the mean would think that it's just $\displaystyle \frac{250}{4}=62.5$

but for the variance I'm not too sure but would think that it's $\displaystyle \frac{250}{4^2}=15.625$

are these correct?