Probability Workbook For Dummies

Appendix A

Tables for Reference

This appendix includes commonly used tables for finding probabilities for three important distributions: the binomial distribution, the normal distribution, and the Poisson distribution.

Binomial Table

Table A-1 shows the cumulative distribution function (cdf) for the binomial distribution (refer to Chapter 8). The cumulative probability is the total probability up to and including any given point. To use Table A-1, you need three pieces of information from the particular problem you’re working on:

• The sample size, n
• The probability of success, p
• The value of X for which you want the cumulative probability

After you have this information, find the portion of Table A-1 devoted to your n and look at the row for your x and the column for your p. Intersect that row and column, and you’ll see the probability that X is less than or equal to your x. To get the probability of being strictly less than, greater than, greater than or equal to, or between two values of X, you manipulate the values of Table A-1, using the steps found in Chapter 8. For values of n less than 5, use the binomial formula to calculate your probabilities (see Chapter 8).

TABLE A-1 The cdf of the Binomial Distribution

Numbers in the table represent P(X ≤ x)
n = 5
	p
x	.01	.05	.10	.20	.25	.30	.40	.50	.60	.70	.75	.80	.90	.95	.99
0	.951	.774	.590	.328	.237	.168	.078	.031	.010	.002	.001	.000	.000	.000	.000
1	.999	.977	.919	.737	.633	.528	.337	.187	.087	.031	.016	.007 ...