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Statistics for Decision- Making in Business - Maricopa Community ...

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This def<strong>in</strong>ition is great, but it still does not resolve our crisis: how do we multiply on a specific<br />

number of sequential whole numbers<br />

Here‟s a little trick: write the factorial out, then divide out the factors that are not needed. For us,<br />

this means:<br />

⏟<br />

⏟<br />

But this is the same th<strong>in</strong>g as:<br />

In a similar way, we can write the denom<strong>in</strong>ator of our probability by:<br />

Be<strong>for</strong>e we push this too far and get ourselves <strong>in</strong>to a trap, let‟s consider a different example with a<br />

smaller sample space.<br />

Suppose that there are only 3 bushels of corn and that only one is contam<strong>in</strong>ated with E. coli.<br />

Aga<strong>in</strong>, let‟s say that two are shipped out. Then,<br />

( )<br />

If you recall the tabular approach to th<strong>in</strong>k<strong>in</strong>g about this, we might show the possibilities <strong>for</strong><br />

uncontam<strong>in</strong>ated bushels, U1 and U2, and the way <strong>in</strong> which they can appear:<br />

1 st Bushel<br />

2 nd Bushel<br />

U1<br />

U1<br />

U2<br />

U2<br />

We know that the pairs (U1, U1) and (U2, U2) <strong>for</strong> the 1 st and 2 nd bushels cannot be possible,<br />

s<strong>in</strong>ce that particular bushel is removed from the population. So, we denote that <strong>in</strong> the table by<br />

black<strong>in</strong>g-out those cells:<br />

<strong>Statistics</strong> <strong>for</strong> <strong>Decision</strong>-<strong>Mak<strong>in</strong>g</strong> <strong>in</strong> Bus<strong>in</strong>ess © Milos Podmanik Page 120

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