英语好的兼数学好的高手们 我这有这样一道英文数学题 好晕的啊An ordered list of four numbers is called a quadruple.A quadruple (p,q,r,s) ≥ 0 is chosen at random such that2p+q+r+s=4What is the probability that p+q+r+s=3?A) 3
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英语好的兼数学好的高手们 我这有这样一道英文数学题 好晕的啊An ordered list of four numbers is called a quadruple.A quadruple (p,q,r,s) ≥ 0 is chosen at random such that2p+q+r+s=4What is the probability that p+q+r+s=3?A) 3
英语好的兼数学好的高手们 我这有这样一道英文数学题 好晕的啊
An ordered list of four numbers is called a quadruple.
A quadruple (p,q,r,s) ≥ 0 is chosen at random such that
2p+q+r+s=4
What is the probability that p+q+r+s=3?
A) 3/22 B) 3/11 C) 3/19 D) 6/19 E) 2/7
英语好的兼数学好的高手们 我这有这样一道英文数学题 好晕的啊An ordered list of four numbers is called a quadruple.A quadruple (p,q,r,s) ≥ 0 is chosen at random such that2p+q+r+s=4What is the probability that p+q+r+s=3?A) 3
这题的大意就是说
有个有序数列(p,q,r,s)在大于等于0的前提下,它们之间的关系是随机抽取的如 2p+q+r+s=4,问随机抽取时抽到满足p+q+r+s=3的概率是多少.
A) 3/22 B) 3/11 C) 3/19 D) 6/19 E) 2/7
因为是有序的数列所以得出这四个数的要满足2p+q+r+s=4的话,可能性如下：
p可能是0
q可能是0,1
r可能是0,1,2
s可能是0,1,2,3,4
一共有1+2+3+5=11种组合 C(1,1)+C(2,1)+C(3,1)+C(5,1)得出
然而由上面结论得出,要满足p+q+r+s=3的话只有下面三种：
0003
0012
0111
答案选B