只有两种可能性,要不就是3个偶数相加,要不就是2个奇数加1个偶数
偶数有2,4,6,8
奇数有1,3,5,7,9
3个偶数相加有246,248,268,468共4种
2个奇数加1个偶数有132,134,136,138,152,154,156,158,172,174,176,178,192,194,196,198,352,354,356,358,372,374,376,378,392,394,396,398,572,574,576,578,592,594,596,598,792,794,796,798共40种
可能的结果有40+4=44种,总的结果有123,124,125,126,127,128,129..28+21+15+10+6+3+1=84种
概率为44/84=11/21