Chapter 6.3, Problem 106E

To determine

To explain: The reason of checking $np\text{ and }np\ge 10$ to use the normal approximation to binomial probabilities.

Explanation of Solution

To use the normal approximation to binomial probabilities whether $np\text{ and }np\ge 10$ or not is checked because there is a huge difference in the shape of both the binomial and normal distributions. Thus, to convert the shape of binomial distribution to normal distribution $np\text{ and }np\ge 10$ is used.