AMC8 2007

AMC8 2007 · Q4

AMC8 2007 · Q4. It mainly tests Basic counting (rules of product/sum).

A haunted house has six windows. In how many ways can Georgie the Ghost enter the house by one window and leave by a different window?

一个鬼屋有六个窗户。Georgie the Ghost可以通过一个窗户进入房子并从另一个不同窗户离开，有多少种方式？

(A) 12 12

(B) 15 15

(D) 30 30

(E) 36 36

Answer

Correct choice: (D)

正确答案：（D）

Solution

(D) Georgie has 6 choices for the window in which to enter. After entering, Georgie has 5 choices for the window from which to exit. So altogether there are $6 \times 5 = 30$ different ways for Georgie to enter one window and exit another.

(D) Georgie 有 6 种选择可以从某个窗户进入。进入后，Georgie 有 5 种选择可以从某个窗户离开。因此总共有 $6 \times 5 = 30$ 种不同的方法让 Georgie 从一个窗户进入并从另一个窗户离开。

Topics

CP.001 Basic counting (rules of product/sum)