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(a) P(A n B) = P(A)*P(B) = 0.3*0.5 = 0.15. ANSWER
(b) P(A U B) = P(A) + P(B) - P(A n B) = 0.3 + 0.5 - 0.15 = 0.65. ANSWER
Solved. // Standard and classic formulas for probabilities.
See any textbook on probability - - - for example, your own textbook.
HINT. In order for to see formulas in your textbook, you should OPEN your textbook first.
Next, you should FIND appropriate formulas there.