## Thinking Mathematically (6th Edition)

Published by Pearson

# Chapter 11 - Counting Methods and Probability Theory - 11.3 Combinations - Exercise Set 11.3 - Page 709: 73

#### Answer

Does not make sense.

#### Work Step by Step

A password implies the importance of order of the letters. For example, "wand" and "dawn" are different orderings of the same four letters and make two different passwords. Order is important. Permutations should be used, not combinations. The formula for ${}_{n}P_{r}$ should be used.

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