Answer 1

Given: \[P\left( A \right) = \frac{1}{3}, P\left( B \right) = \frac{1}{5} \text{ and }  P\left( A \cap B \right) = \frac{1}{15}\]

Given:
P (A) = 0.35, P (A ∪ B) = 0.6 and P (A ∩ B) = 0.25
By addition theorem, we have:
P (A ∪ B) = P(A) + P (B) - P (A ∩ B)
          0.6  = 0.35 + P (B) - 0.25
       P (B) = 0.6 - 0.35 + 0.25
         = 0.6 - 0.1 = 0.5