# Someone Please Re Anwser Question Anwser Received Wrong Unfortunately Correct One 540 Reac Q17779194

Can someone please re-anwser the question? The anwser that Ireceived was wrong unfortunately. The correct one for a is 540, buthow should I reach it?
ooo Tele2 4 12:19 Expert Q&A You have five letters A,B,C,D,E a) how many words with 4 letters can you build if each and every letter can be used maximally twice (I.e. a letter can appear in a word 0,1, or 2 times) b) Assume that you at random choose a word according to a). Calculate the probablity that you get a word whose first two letters are A! Please explain explicitly with the permutation/combination techniques used here! Many thanks 1 SOLUTION Anonymous about 1 hour later a) there are 3 cases: no letter is repeated, one letter is repeated once, 2 letters are repeated once. now for no letter is repeated we can select 4 letters from the given 5 letters in sC4 5 ways and can be arranged in 4 24 ways. so total number of letters 5*24 120 now for one letter is repeated once, we are actually selecting 3 letters from the 5 and repeating one of them. so from 5 letters 3 can be selected in Sc3 10 ways and the letter that is repeated can be selected from 3 Show transcribed image text