Question 1119915: Please help me solve this in simple way. Thank You.
What is the probability that if 5 letters are typed, no letters are repeated?
The probability that no letters are repeated is...
Answer by solver91311(24713)   (Show Source):
You can put this solution on YOUR website!
I'm going to presume that by "letters" you mean the alphabetic characters "a" through "z". This problem will still have two different answers depending on whether you consider "A" and "a" the same or different. One has to assume that you are referring to the English alphabet as well.
If they are the same, then there are 26 possibilities for the first character, then once the first character is chosen, in order to avoid duplication there are only 25 possibilities for the second character. Hence, for the first two characters, there are 26 times 25 or 650 possibilities. For each of those possibilities there are 24 ways to choose the third character, and so on. So, in total, the number of ways to create a five character alphabetic string without repetition would be:
But the total number of possible five alphabetic character strings if you do allow duplication is:
Hence, the probability of a random five-character alphabetic string is:
You can do your own arithmetic.
By the way, if "A" and "a" are different, then:
John
My calculator said it, I believe it, that settles it
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