If you've never done stats, why do you have to answer this question?

As the mean count is 25 dpm this specifies the distribution parameter $\lambda=25$

i) is just the Cumulative distribution function (CDF) of the specified Poisson distribution evaluated at 0.

ii) is 1 - CDF(2)

you can find the CDF on wiki or by integrating the PDF of the Poisson distribution.