作业帮一道关于概率的英文数学题
来源：学生作业帮 编辑：作业帮 分类：英语作业 时间：2024/07/03 13:42:37
一道关于概率的英文数学题
7) A box contains 3 red,4 white and 5 blue discs.Three discs are selected at random
from the box.Find the probability that:
a) all three discs are the same colour,if the selection is with replacement
b) all three discs are of different colours,if the selection is without replacement
翻译人人都会
7) A box contains 3 red,4 white and 5 blue discs.Three discs are selected at random
from the box.Find the probability that:
a) all three discs are the same colour,if the selection is with replacement
b) all three discs are of different colours,if the selection is without replacement
翻译人人都会
额````翻译楼上的已经做了,我就直接解答了.
a、颜色相同有3种情况,我们要分别计算
就是1/4*2/11*1/10+1/3*3/11*1/5+5/12*4/11*3/10=3/44就是这个概率啦~
b、这个跟上面挺像的,就是有点麻烦
1/4*4/11*1/2+1/4*5/11*2/5+1/3*3/11*1/2+1/3*5/11*3/10+5/12*3/11*2/5+5/12*4/11*3/10=3/11
真是累人,就是要分情况讨论,倒不是很难,就是不同顺序的搭配
a、颜色相同有3种情况,我们要分别计算
就是1/4*2/11*1/10+1/3*3/11*1/5+5/12*4/11*3/10=3/44就是这个概率啦~
b、这个跟上面挺像的,就是有点麻烦
1/4*4/11*1/2+1/4*5/11*2/5+1/3*3/11*1/2+1/3*5/11*3/10+5/12*3/11*2/5+5/12*4/11*3/10=3/11
真是累人,就是要分情况讨论,倒不是很难,就是不同顺序的搭配