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標題:

F.7 Probability [20points]

發問:

Two urns contain some coloured balls.Urn A contains 12 balls: 8 are black, 4 are white.Urn B contains 15 balls: 9 are black , 6 are white.A ball is drawn at random from urn A to placed in urn B.A ball is thendrawn at random from urn B, which now contains sixteen balls.What is the probability that the ball... 顯示更多 Two urns contain some coloured balls. Urn A contains 12 balls: 8 are black, 4 are white. Urn B contains 15 balls: 9 are black , 6 are white. A ball is drawn at random from urn A to placed in urn B. A ball is thendrawn at random from urn B, which now contains sixteen balls. What is the probability that the ball drawn from urn B is black? Ans : 29/48 Q: Given that the ball drawn from urn B was black, what is the probability that the ball drawn from urn A was also black? Ans: 20/29

最佳解答:

1) P(The ball drawn from urn B is black)= P(A black ball is drawn from urn A to placed in urn B and then a black ball drawn from urn B) + P(A white ball is drawn from urn A to placed in urn B and then a black ball drawn from urn B)= (8/12)(10/16) + (4/12)(9/16)= 29/48 2) P(The ball drawn from urn A was also black given that the ball drawn from urn B was black)= P(A black ball is drawn from urn A to placed in urn B and then a black ball drawn from urn B) / P(The ball drawn from urn B is black)= (8/12)(10/16) / (29/48)= 20/29

其他解答:

(a) P(the ball from urn B is black) = P(the ball from urn B is black|the ball from urn A is black)P(the ball from urn A is black) + P(the ball from urn B is black|the ball from urn A is white)P(the ball from urn A is white) = (10/16)(8/12) + (9/16)(4/12) = 29/48 (b) (10/16)(8/12)/[(10/16)(8/12) + (9/16)(4/12)] = 20/29

• 有關1元二次方的文字題精品店老闆以48元成本價買入一批水晶杯，運輸途中打碎了2隻，但若他以每隻比成本高3元的價錢售出餘下的水晶杯，他共可獲利22元。 a 求他共買入多少隻水昌杯b 每隻杯售價是多少- 一元2次文字題-
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• 有關1元二次方的文字題精品店老闆以48元成本價買入一批水晶杯，運輸途中打碎了2隻，但若他以每隻比成本高3元的價錢售出餘下的水晶杯，他共可獲利22元。 a 求他共買入多少隻水昌杯b 每隻杯售價是多少- 一元2次文字題-
• neway新年幾時開--
• 高中數學 直線

 

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