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标题: GWD 7-14 [打印本页]

作者: xdrertty    时间: 2004-12-22 07:42     标题: GWD 7-14

Q14:Six cards numbered from 1 to 6 are placed in an empty bowl. First one card is drawn and then put back into the bowl; then a second card is drawn. If the cards are drawn at random and if the sum of the numbers on the cards is 8, what is the probability that one of the two cards drawn is numbered 5 ?

A. 1/6

B. 1/5

C. 1/3

D. 2/5

E. 2/3

这题怎么做啊

MINE B

ANS D


作者: baby11    时间: 2004-12-22 07:43

5種可能

( x y) = ( 2 6 ) ( 6 2 ) ( 3 5 ) ( 5 3 ) (4 4)

兩個有5 ==>ans=2/5






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