maths(more about probaility)

用戶15946

2007-11-11 5:29 am

1.A card is picked at random from a pack of 52 playing-cards(without jokers).Find the probability of getting neither a diamond,a king nor a queen.

2.There are balls in red ,yellow,blue,white and green in a bag.If a ball is drawn at random,the probailities of drawing balls in different colours are as follows.
P(red)=1/6,P(yellow)=1/4,
P(blue)=1/8,P(white)=3P(green)
Find the probability of drawing a green ball.

回答 (1)

HaHa

2007-11-11 5:50 am

✔ 最佳答案

1.Since there are 13 diamond card, so the number of cards that are not diamond is
52-13=39
and there are 3 kings and 3 queens left in the remainning, so the numbers of cards that are not neither a diamond, a king nor a queen is 39-3-3=33
therefore the probability of getting neither a diamond, a king nor a queen is 33/52

2. Since adding all the probabilities is 1
therefore P(red)+P(yellow)+P(Blue)+P(white)+P(green)=1
subsitute P(white)=3P(green) into it, then we have
P(red)+P(yellow)+P(Blue)+4P(green)=1
1/6+1/4+1/8+4P(green)=1
therefore, P(green)=1196

2007-11-10 21:53:06 補充：
the ans is 11/96

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