break it down into cases

at most one day of rain in 3 days to me means we could have:

norain norain norain ----> (1/3)^3 = 1/27
rain norain norain -------> 2/3(1/3^2 = 2/27
norain rain norain -------> same as above = 2/27
norain norain rain -------> same as above = 2/27

since there is an OR between these probabilities and there are no overlaps we simply add these
so 1/27 + 3(2/27) = 7/27

The probability of rain on any given day is 2/3. What is the probablity of at most one day of rain during the next three days...i don't get this problem plz explain the steps :)

1 answer

P(A and B) = P(A) * P(B)
2/3 = rain
1/3 = no rain

2/3 * 1/3 = 2/9