Given: P(A) = 0.60, P(A or B) = 0.85 and P(A and B) = 0.42
We know that, P(A or B) = P(A) + P(B) – P(A and B)
By substituting values in the above formula, we get
0.85 = 0.60 + P(B) – 0.42
0.85 = 0.18 + P(B)
0.85 – 0.18 = P(B)
0.67 = P(B)
or P(B) = 0.67