SAT数学(英文数学双强者优先)If j is chosen at random from the set(4,5,6) and k is chosen at random from the set(10,11,12),what is the probability that the product of j and k is divisible by (要列式,不要列举)

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SAT数学(英文数学双强者优先)If j is chosen at random from the set(4,5,6) and k is chosen at random from the set(10,11,12),what is the probability that the product of j and k is divisible by (要列式,不要列举)
SAT数学(英文数学双强者优先)
If j is chosen at random from the set(4,5,6) and k is chosen at random from the set(10,11,12),what is the probability that the product of j and k is divisible by (要列式,不要列举)

SAT数学(英文数学双强者优先)If j is chosen at random from the set(4,5,6) and k is chosen at random from the set(10,11,12),what is the probability that the product of j and k is divisible by (要列式,不要列举)
原题翻译:从集合(4,5,6)中任意取一个数j,从集合(10,11,12)中任意取一个数k,那么j和k的乘积能被5整除的概率是多少?
要使j*k能被5整除,那么j和k至少有一个是5的倍数,可以从反面考虑,如果j*k不能被5整除,那么j和k都不是5的倍数,所以j*k不能被5整除的概率是(2/3)*(2/3)=4/9,故j*k能被5整除的概率是1-4/9=5/9

5/9

说穿了就是4,5,6里选个j,从10,11,12里选个k,然后乘起来,其中能被5整除的几率是多少,,,product是积的意思,divisible是整除的意思,这题我前两天刚做过