The number of four-letter words (including nonsense words) using four different letters from A through Jis 210.

A First Course in Probability (10th Edition)
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Chapter1: Combinatorial Analysis
Section: Chapter Questions
Problem 1.1P: a. How many different 7-place license plates are possible if the first 2 places are for letters and...
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Why the reversed logic? Why can't it be answered with C(10, 4) = 210?

Answer to Problem 40E
The number of four-letter words (including nonsense words) using four different letters from A through Jis
210.
Explanation of Solution
Given information:
The alphabets from A to J.
Formula used:
The bionomial theorem C (n,r) =
Calculation:
To obtain four-letter words (including nonsense words) using four different letters form A through J can be
string as ABCDEFGHIJ and remove six alphabet. This sample is just an unordered selection of 6 digits out of
10. We are concerned here with combinations. Since the six digits can be selected in selected in C (10, 6)
ways. Numerically we have
C(10,6)
=
=
10!
6!(10-6)!
10!
6!.4!
n!
r!(n-r)! *
10.9.8.7.6.5
6.5.4.3.2.1
= 210
Therefore, the number of four-letter words (including nonsense words) using four different letters from A
through Jis 210.
Transcribed Image Text:Answer to Problem 40E The number of four-letter words (including nonsense words) using four different letters from A through Jis 210. Explanation of Solution Given information: The alphabets from A to J. Formula used: The bionomial theorem C (n,r) = Calculation: To obtain four-letter words (including nonsense words) using four different letters form A through J can be string as ABCDEFGHIJ and remove six alphabet. This sample is just an unordered selection of 6 digits out of 10. We are concerned here with combinations. Since the six digits can be selected in selected in C (10, 6) ways. Numerically we have C(10,6) = = 10! 6!(10-6)! 10! 6!.4! n! r!(n-r)! * 10.9.8.7.6.5 6.5.4.3.2.1 = 210 Therefore, the number of four-letter words (including nonsense words) using four different letters from A through Jis 210.
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