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A contest consists of finding all code words that can be formed from the letters in the word "alpha".Assume that the letter "a" can be used twice but the others at most once:

a)How many five-letter words can be formed?

5*4*3=60 words

b)How many two-letter words can be formed?

with two letter words can be formed is 13

c)How many words can be formed?

5 letter words=60 4 letter words=60 3 letter words=33 2 letter words=13 1 letter words=4 so,60+60+33+13+4=170

Could you please check t for me?

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marked as duplicate by Newb, drhab, John B, loup blanc, N. F. Taussig May 24 '16 at 9:23

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  • $\begingroup$ a), b) correct. c) wrong (check 4 letter words). $\endgroup$ – almagest May 24 '16 at 6:31
  • $\begingroup$ How come a) is correct? You choose 2 slots for a and then 3! for the remaining lettetrs $\endgroup$ – Alex May 24 '16 at 7:28
  • $\begingroup$ @Alex You can also choose where to place the l, the p, and the h, then place the two a's in the two open positions. $\endgroup$ – N. F. Taussig May 24 '16 at 9:21
  • $\begingroup$ Yes of course; i'm not sure why i wrote it $\endgroup$ – Alex May 24 '16 at 9:58