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how many 4-letter passwords can be formed using the letters a, b, c, d, e, f, g if repetition of letters is not allowed and the first letter can only be a, b or c?

Respuesta :

840 are  4-letter passwords can be formed using the letters by permutation .

What are some examples of permutation?

  • A permutation is a set up of things in a specific order. In this arrangement, the components or components of sets are organized in a linear or sequential order.
  • The permutation of the set A=1,6 is 2, for instance, 1,6, and 6,1.
  • The components of set A cannot be arranged in any other way, as you can see.

We are to count all possible 4-letter passwords that can be generated from the letters a, b, c, d, e, f, g .

There are 7 letters in total.

      n = 7 r = 4

 P(n , r ) = 7!/( n - r )!

  P( 7 ,4 ) = 7!/( 7 - 4)!

              = 7!/3!

             = 7 * 6 * 5 * 4 * 3 * 2 * 1/3!

              = 7 * 6 * 5 * 4

               = 840

Learn more about permutation

brainly.com/question/1216161

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