GWS-1-No.7

[游客]

Q7:
A certain university will select 1 of 7 candidates eligible to fill a position in the mathematics department and 2 of 10 candidates eligible to fill 2 identical positions in the computer science department. If none of the candidates is eligible for a position in both departments, how many different sets of 3 candidates are there to fill the 3 positions?

A. 42
B. 70
C. 140
D. 165
E. 315

[游客]

C(7,1)*C(10,2)=315

[QQcandy]

Yes...so what's your question ? :|

[游客]

I found the answer before you answer...

M.L.

[cocaine]

問題就要問他要選3個人出來,其中1人從A7人去抽,另外2人從B10人去抽.

[撥撥]

If none of the candidates is eligible for a position in both departments, how many different sets of 3 candidates are there to fill the 3 Positions?
我想問這句話是什麼意思呢？是指一個人不能兼二邊的位子啊？

另外：
C(10,2) 和 C(10,1) x C(9,1) 的差別在那裡啊？

先謝謝大家

[65kevin]

If none of the candidates is eligible for a position in both departments, how many different sets of 3 candidates are there to fill the 3 Positions?
我想問這句話是什麼意思呢？是指一個人不能兼二邊的位子啊？

另外：
C(10,2) 和 C(10,1) x C(9,1) 的差別在那裡啊？

先謝謝大家

恩... 沒錯, 一個人不能兼兩邊的位子... 那七個後選人和另外十個候選人是要分開來看的

C(10,2) 和 C(10,1) * C(9,1) 的差別在後者是將人選選出來後還要考慮先後排列的順序, 前者只是選兩個人出來, 並不需要考慮先後排列順序

[grady]

為什麼是兩個相乘?
我不太了解最後一句的意思。
我以為是要算兩個相加。