A%20Probability%20Approach%20For%20Solving%20Counting%20Problems

I have seen some very good shortcuts for solving this

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Unformatted text preview: r). I have seen some very good shortcuts for solving this question (and others like it). But I would like to offer you a fast and foolproof method. My method is probability based and I call it "A probability approach for solving counting problems" method. Now let Y be the ... don't worry! No Y is needed, just wanted to sound smart! (And as you know every good math/physics/finance paper starts with "let something be something") So I would like to start with a simple problem, very simple problem: How many integers from 1 to 100 including, has a units digit of 5? A) 5 B) 9 C) 10 D) 11 E) 20 This is a 350 level question; all you need to do is to list the integers that has 5 as the units digit, I call this the basic method, meaning Count(5,15,25,35,45,55,65,75,85,95) = 10. The answer is (C). Using the probability method we can see we have two places for digit in the integer XX and we need to fill in the tens di...
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This document was uploaded on 02/28/2014.

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