GMAT PP-ps-157

[bennent]

157. 16358-!-item-!-187;#058&010761
To furnish a room in a model home, an interior decorator is to select 2 chairs and 2 tables from a collection of chairs and tables in a warehouse that are all different from each other. If there are 5 chairs in the warehouse and if 150 different combinations are possible, how many tables are in the warehouse?

(A) 6
(B) 8
(C) 10
(D) 15
(E) 30
請求思路及解法，對於紅色那段不是很懂語意，謝謝。

[oneseven]

意思是說 如果有五張椅子 有150種不同的組合 問有幾張桌子

設有 n 張桌子

C(5,2) * C(n,2) = 150

所以C(n,2) = 15

可以得 n = 6

[bennentangela]

感謝 原來如此