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

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Probability<br />

Successes Probability<br />

0 0.001<br />

1 0.010<br />

2 0.044<br />

3 0.117<br />

4 0.205<br />

5 0.246<br />

6 0.205<br />

7 0.117<br />

8 0.044<br />

9 0.010<br />

10 0.001<br />

Does this match our expectations The table <strong>in</strong>dicates that gett<strong>in</strong>g 5 heads has the highest<br />

likelihood of all 11 possible events. Even more importantly, the probability of gett<strong>in</strong>g between 4<br />

and 6 heads <strong>in</strong> 10 tosses is<br />

. The probability of gett<strong>in</strong>g very few<br />

or many successes gets to be very unlikely. This data is displayed <strong>in</strong> the histogram below:<br />

0.300<br />

Toss<strong>in</strong>g X Heads <strong>in</strong> 10 Tosses<br />

0.250<br />

0.200<br />

0.150<br />

0.100<br />

0.050<br />

0.000<br />

1 2 3 4 5 6 7 8 9 10 11<br />

Successes<br />

This further validates our argument above.<br />

Additionally, note that the sum of all event probabilities sums to 1. This is necessary and<br />

important <strong>in</strong> describ<strong>in</strong>g the distribution.<br />

Sum of Success Probabilities <strong>in</strong> a B<strong>in</strong>omial Experiment<br />

With trials <strong>in</strong> a b<strong>in</strong>omial experiment, the sum of the probabilities of 0 up to successes must<br />

constitute the sample space and hence equal 1.<br />

That is,<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 152

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