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 6-letter code words to the number of 4-letter code words?
Select the correct option
A) 20 B) 30 C) 35 D) 40 E) 45
Method #1: Using the permutation formula   # of 6 letter code words:   nPr = n! / (n – r)! = 10! / (10 – 6)! = 10*9*8*7*6*5   # of 4 letter code words:   nPr = 10! / (10 – 4)! = 10*9*8*7   # of 5 words / # of 4 words = (10*9*8*7*6*5)/(10*9*8*7)= 
<gadget id="calculator">(10*9*8*7*6*5)/(10*9*8*7)</gadget>
<output>30</output>
30   30
<result>B</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 6-letter code words to the number of 4-letter code words?