The events A and B are independent, the probability that event A occurs is greater than 0, and the probability that event A occurs is twice the probability that event B occurs. The probability that at least one of events A and B occurs is 14 times the probability that both events A and B occur. What is the probability that event A occurs? Choose the correct answer: A) 77 / 2 B) 1 / 7 C) 78 / 85 D) 1 / 5 E) 47 / 85

Rationale: "let us say probability of a occuring is a . let us say probability of b occuring is b . a = 2 b probability ( either a or b or both ) = 14 times probability ( a and b ) a * ( 1 - b ) + b * ( 1 - a ) + ab = 14 * ab substituting a = 2 b in the second equation : 2 b * ( 1 - b ) + b * ( 1 - 2 b ) + 2 b * b = 14 * 2 b * b 3 b - 2 b ^ 2 = 28 b ^ 2 3 b = 30 b ^ 2 b = 3 / 30 = 1 / 10 so , a = 2 b = 1 / 5 the correct answer is d ."
Answer: D