[求助]pp-T2-DS158

husband

pp-T1-DS158
158. Each of the 25 balls in a certain box is either red, blue, or white and has a number from 1 to 10 painted on it. If one ball is to be selected at random from the box, what is the probability that the ball selected will either be white or have an even number painted on it? (1) The probability that the ball will both be white and have an even number painted on it is 0. (2) The probability that the ball will be white minus the probability that the ball will have an even number painted on it is 0.2. Ans:E 請教這題如何解

plato1983

题目所问的可以用公式P（probability）either=P（white）+P（even）-P（both）来解出。
但A，B条件只给出了P（both）和P（white）-P（even），条件不足。

husband

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