Final answer:
The normal distribution is used to approximate binomial probabilities by simplifying the calculation process.
Step-by-step explanation:
Normal distribution, is a symmetrical probability distribution that forms a bell-shaped curve when graphed. In this statistical concept, data tends to cluster around the mean, with the majority of values falling within one or more standard deviations from the average, as described by the empirical rule.
The normal distribution is used to approximate binomial probabilities in order to simplify the calculation process. It is required that both np (the mean) and nq (the standard deviation) be at least 5, or preferably 10, in order for the approximation to be accurate. This is because when both np and nq are large enough, the shape of the binomial distribution becomes similar to the shape of the normal distribution.