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 6-letter code words?
Choose the correct option:
A) 1 B) 1/4 C) 1/5 D) 1/3 E) 1/2
Method #1: Using the permutation formula   # of 5 letter code words:   nPr = n! / (n – r)! = 10! / (10 – 5)! = 10*9*8*7*6   # of 6 letter code words:   nPr = 10! / (10 – 6)! = 10*9*8*7*6*5   # of 5 words / # of 4 words = (10*9*8*7*6)/(10*9*8*7*6*5) = 1/5   1/5
<result>C</result>
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 6-letter code words?