Remember how nasty our friend the binomial distribution can get sometimes? Well, the normal distribution may be able help us out during these difficult times under the right conditions. Recall from Chapter 9 that the binomial equation will calculate the probability of *r* successes in *n* trials with *p* = the probability of a success for each trial and *q* = the probability of a failure. If *np* ≥ 5 and *nq* ≥ 5, we can use the normal distribution to approximate the binomial.

As an example, suppose my statistics class is composed of 60 percent females. If I select 15 students at random, what is the probability that this group will include 8, 9, 10, or 11 female students? ...

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