Given:

\(P( \text{no oil}) = 0.30\)

a. Complement rule:

\(P( \text{not} A ) = 1 - P(A)\)

Use the complement rule:

\(P(\text{oil}) = 1 - P(\text{no oil}) = 1 - 0.30 = 0.70\)

b. We are most likely to find the type of soil, when we have found medium-quality oil.

The probabilities remain unchanged> becase the given probability only effect the probability of finding soil and not the probability of finding oil.

\(P( \text{no oil}) = 0.30\)

a. Complement rule:

\(P( \text{not} A ) = 1 - P(A)\)

Use the complement rule:

\(P(\text{oil}) = 1 - P(\text{no oil}) = 1 - 0.30 = 0.70\)

b. We are most likely to find the type of soil, when we have found medium-quality oil.

The probabilities remain unchanged> becase the given probability only effect the probability of finding soil and not the probability of finding oil.