5张卡片上分别写着1,2,3,4,5,从中任取两张,取出的两个数的和是偶数的...答:所有的结果为(1,2),(1,3),(1,4),(1,5),(2,3),(2,4),(2,5),(3,4),(3,5),(4,5)共10个,其中和为偶数的有(1,3),(1,5),(2,4),(3,5),共4个,因此取出的两个数的和是偶数的可能性是4/10=2/5 ...
有五张写有数字的卡片,分别写着1、2、4、5、8,从中任意取3张卡片并排...答:偶数即个位是偶数:2.4.8 3×(3×4)=3×12=36种:个位数是2:142,152,182,412,452,482,512,542,582,812,842,852 个位数是4:124,154,184,214,254,284,514,524,584,814,824,854 个位数是8: 128,148,158,218,248,258,418,428,458,518,528,548,所以,一共36个 ...