The variation that occurs due to selecting a single sample from the population is the?

The (Answer)states that the sampling distribution of the sample mean, is approximately normally distributed for a large sample size n regardless of the shape of the underlying population (spelling counts)

For samples of n = 30, for most populations, the sampling distribution of the mean will be approximately normally distributed,

In estimating the population mean with the population standard deviation unknown, if the sample size is 23, there will be ____ degrees of freedom.