You are choosing a computer password. The password has 3 letters followed by 3 digits.
a. How many passwords are possible if no letter or digit can be repeated and the letters have to be lowercase?
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i need help. i know who to do the problem if there was allowed repeats but what do i do now? what math should i do? help!
2007-01-21 11:35:19 · 5 answers · asked by kitty 2 in Science & Mathematics ➔ Mathematics
thanks every one!! i understand now. thanks for all your help!
2007-01-21 11:54:51 · update #1
The probability is 1/26 * 1/25 * 1/24 * 1/10 * 1/9 * 1/8 = 1/11232000
2007-01-21 12:54:20 · answer #1 · answered by Tan D 7 · 0⤊ 0⤋
three letter password: xxx###
well there is 26 letters and 3 possible letters can be used
so (26*25*24) = 15600 possibilities
there is 10 digits (0 - 9) and 3 possible numbers
so (10*9*8) = 720 possibilities
Multiple these two values
(15600)(720) = 11 232 000 possibilities
2007-01-21 19:43:32 · answer #2 · answered by Donny Dutch 4 · 1⤊ 0⤋
26 * 25 * 24 * 10 * 9 * 8 = 11232000
first can be one of 26 letters
second has to be one of 25 letters (not the same as the first)
third has to be on of 24 letters (different than the first 2)
fourth - is a digit is one of 10 different digits (0123456789)
fifth is one of 9 digits, sixth is one of 8 digits
11,232,000 combinations
2007-01-21 19:41:20 · answer #3 · answered by Bill F 6 · 1⤊ 0⤋
26*25*24*10*9*8 = 11232000 possibilities
the first character must be a letter. there are 26 lettters, therefore 26 possibilities.
the second lcharacter must also be a letter, there are 26 letter, but there is one that can no longer be used, so there are 25 possibilities. the rest is evident i think.
2007-01-21 19:41:18 · answer #4 · answered by Michael Dino C 4 · 1⤊ 0⤋
26*25*24*10*9*8
26 ways to pick 1st letter
25 ways to pick second one (given that one letter is used up as 1st)
... and so on.
2007-01-21 19:40:01 · answer #5 · answered by Anonymous · 1⤊ 0⤋