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.)
Choose the correct option:
A) 20
B) 92
C) 300
D) 372
E) 476
# of letters = 8, # of ways to choose 3 letters out of 8 when order matters is P38=8!/(8−3)!=336 which means that there can be 336 different sequences. As 36 sequences were not assigned then  336-36= 
<gadget id="calculator"> 336-36</gadget>
<output>300</output>
300 sequences were assigned, so there are 300 participants.   ANSWER:300
<result>C</result>
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.)