How many 3-letter code words are possible using the first 10 letters of the English alphabet, if no letter can be repeated ?
First letter of the code word can be selected in 10 ways. After the selection of the first letter, we have nine letters. Hence, the second letter can be selected in nine ways. According to Fundamental principal of Counting(FPC), first two letters can be selected in 10 x 9 ways.
Similarly third letter can be selected in eight ways . According to FPC , number of ways of selecting Three letters out of ten letters of English alphabet = 10 x 9 x 8 ways = 720 ways...........
Sol :
First letter of the code word can be selected in 10 ways. After the selection of the first letter, we have nine letters. Hence, the second letter can be selected in nine ways. According to Fundamental principal of Counting(FPC), first two letters can be selected in 10 x 9 ways.
Similarly third letter can be selected in eight ways . According to FPC , number of ways of selecting Three letters out of ten letters of English alphabet = 10 x 9 x 8 ways = 720 ways...........
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