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老方那發的
數學一題
If two numbers are to be selected from the first ten positve integers with
replacement, what is the probability that at least one of them is even?
A. 2/9 B. 1/4 C. 1/2 D. 3/4 E. 7/9
我覺得答案是E
可是答案給的是D
我的算法是 C(10,2)-C(5,2) 35 7
-----------------------= ----------- = -----
C(10,2) 45 9
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08/13 20:24, , 1F
08/13 20:24, 1F
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08/13 20:25, , 2F
08/13 20:25, 2F
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08/13 20:38, , 3F
08/13 20:38, 3F
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08/13 20:58, , 4F
08/13 20:58, 4F
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