need help, please!

來源: 於 2010-02-03 07:55:24 [舊帖] [給我悄悄話] 本文已被閱讀：次

If two regular six-sided dice are thrown, the probability that the sum will be a prime number is
a. 5/36 b. 1/6 c. 5/12 d. 1/2 e. 2/9



thank you very much!