We can also estimate the proportion of a population by constructing a confidence interval from a sample. As you might recall from Chapter 13, proportion data follow the binomial distribution that can be approximated by the normal distribution under the following conditions:
*np* ≥ 5 and *nq* ≥ 5

where:
*p* = the probability of a success in the population
*q* = the probability of a failure in the population (*q* = 1 - p)

Suppose I want to estimate the proportion of home shopping customers who are female based on the results of a sample. In Chapter 13, we learned that we can calculate the proportion of a sample using:

The confidence ...

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