Answer:
A sample mean can be assumed to be the value from population having a normal distribution when both or either of these conditions is met:
1) The population from which the sample is being taken is Normally distributed. So in this case, if the population of grade-point averages is normally distributed, the sample mean would be treated as a value from a population having a normal distribution
2) The sample size is greater than 30. If we do not have knowledge about the population, but the sample size is greater than 30, the sample mean can be considered as a value from a population having a normal distribution.
