I have to solve the following question:

1, What is the probability of rain on any given working day (Mon-Fri) given that that probility from records suggest 30%.

i, the probability of no rain on 3 consecutive working days

ii, the probaility that there will be rain on at least 1 of 4 consecutive days.

how is this calculated and what is the equation for doing so? Please be simple and detailed in the response as I'm picking this stuff up as I go along.

Many thanks in advance.

Colin