If a code word is defined to be a sequence of different letters chosen from the 10 letters A, B, C, D, E, F, G, H, I, and J, what is the ratio of the number of 5-letter code words to the number of 4-letter code words?
A. 5 to 4
B. 3 to 2
C. 2 to 1
D. 5 to 1
E. 6 to 1
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5 comments:
10P5 / 10P4 == 6 / 1
answer = E
E
10p5:10p4=6:1
E
ways of choosing 5 letters out of 10 is 10C5 but then there are 5! ways to arrange them too… or 10P5. so its basically.
10P5 : 10P4 :: 6 : 1
ans. [E]
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