CMATPrep一題請問

[whoops]

All of the stocks on the over-the -counter market are designated by either a 4-letter oe a 5-letter code that is created by using the 26 letters of the alphabet. Which of the following gives the maximum number of different stocks that can be designated with this codes?

1)2*26的五次方
2)26*26的四次方
3)27*26的四次方
4)26*25的五次方
5)27*26的五次方

Ans-C
請問如何解題?

[danny214]

如果字母可以重複選取
4-letter code 有26*26*26*26=26^4種
5-letter code 有26*26*26*26*26=26^5種
答案兩個加起來
(26^4)+(26^5)
=(26^4)*(26+1)
=27*26^4

有錯請改正^^

[whoops]

如果字母可以重複選取
4-letter code 有26*26*26*26=26^4種
5-letter code 有26*26*26*26*26=26^5種
答案兩個加起來
(26^4)+(26^5)
=(26^4)*(26+1)
=27*26^4

有錯請改正^^

實在是太汗顏了..
一直卡在aiphabet這個字以為是aiphabetical
必須要照字母順序來看..