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4.3 THE BINOMIAL DISTRIBUTION 107<br />

FIGURE 4.3.1 Schematic representation of solutions to Example 4.3.4 (the relevant<br />

numbers of successes and failures in each case are circled).<br />

that when n is small relative to N, the binomial model is appropriate. Some writers say<br />

that n is small relative to N if N is at least 10 times as large as n.<br />

Most statistical software programs allow for the calculation of binomial probabilities<br />

with a personal computer. EXCEL, for example, can be used to calculate individual or cumulative<br />

probabilities for specified values of x, n, and p. Suppose we wish to find the individual<br />

probabilities for x = 0 through x = 6 when n = 6 and p = .3. We enter the numbers<br />

0 through 6 in Column 1 and proceed as shown in Figure 4.3.2. We may follow a similar<br />

procedure to find the cumulative probabilities. For this illustration, we use MINITAB and<br />

place the numbers 1 through 6 in Column 1. We proceed as shown in Figure 4.3.3.<br />

Using the following cell command:<br />

BINOMDIST(A*, 6, .3, false), where A* is the appropriate cell reference<br />

We obtain the following output:<br />

0 0.117649<br />

1 0.302526<br />

2 0.324135<br />

3 0.185220<br />

4 0.059535<br />

5 0.010206<br />

6 0.000729<br />

FIGURE 4.3.2 Excel calculation of individual binomial probabilities for x = 0 through<br />

x = 6 when n = 6 and p = 3.

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