Critical Thinking: Brain Teaser

Critical Thinking: Brain Teaser A requirement for using the normal distribution to approximate the distribution is that both np > 5 and np > 5. Since we usually do not know p, we estimate p by and q by . Then we require that and . Show that the conditions and are equivalent to the condition that out of n binomial trials, both the number of successes r and the number of failures n - r must exceed 5.