Following the manner on how you solve the problem, I realized that the first question could also be answered by getting the complement/not the probability of both wells producing oil: 1-.02=0.98
Welcome to the forum.
What is the probability that at most one well produces oil?
That can mean 0 or 1 so
.8 + .18 = .98
At least one?
That means 1 or 2 which is the complement of none.
1 - .8 = .2
Please help me with this problem: An oil-prospecting firm plans to drill 2 exploratory wells. Past evidence shows that the probability that neither well produces oil is 0.8; the probability that exactly one well produces oil is 0.18; and the probability that both wells produces is 0.02. What is the probability that at most one well produces oil? At least one?