Suppose that Box I contains 6 red balls and 9 green balls, and Box II contains 8 red balls and 12 green balls. All the balls of Box I and Box II are mixed together and a ball is chosen at random from them. Let \(E_1\) be the event that the ball chosen belonged to Box I and let \(E_2\) be the event that the ball chosen belonged to Box II. Let \(F_1\) be the event that the ball chosen is red and let \(F_2\) be the event that the ball chosen is green. Then which of the following statements is (are) TRUE?
Total balls = 15 + 20 = 35. Red balls = 6 + 8 = 14 and green balls = 9 + 12 = 21. Therefore P(F_1)=14/35=2/5 and P(F_2)=21/35=3/5. Also P(E_1)=15/35=3/7 and P(E_2)=20/35=4/7. Since P(F_1|E_1)=6/15=2/5=P(F_1), the events E_1 and F_1 are independent, so (A) is true. Similarly, P(F_2|E_2)=12/20=3/5=P(F_2), hence E_2 and F_2 are also independent, making (B) false. Further, P(F_1|E_1)=6/15=2/5 and P(F_1|E_2)=8/20=2/5, so (C) is true. Finally, P(F_1|E_1)=2/5 while P(F_2|E_2)=3/5, therefore (D) is false. Hence the correct options are (A) and (C).
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