[問題]天山5-3

[narofara]

Q3
Each participant in a certain study was assigned a sequence of 3 different letters from the set {A, B, C, D, E, F, G, H}. If no sequence was assigned to more than one participant and if 36 of the possible sequences were not assigned, what was the number of participants in the study? (Note, for example, that the sequence A, B, C is different from
the sequence C, B, A.)

A. 20
B. 92
C. 300 ←ans
D. 372
E. 476

又遇到問題了...
請各位好心的高手幫我解答一下吧~

[sklpeng]

8個英文字母中任取3個排列,順序不同意義不同
所以用P8取3得336
有多出36個可能
故只有336-36=300個