The number of vacation days taken by the employees of a company is normally distributed with a mean of 14 days and a standard deviation of 3 days. Is this a case of sample standard deviation or population standard deviation? What are some differences between sample standard deviation and population standard deviation?

For the next employee, what is the probability that the number of days of vacation taken is less than 10 days? What is the probability that the number of days of vacation taken is more than 21 days?

Please explain how you get the answer