In a confidence interval with a 95% confidence level between 300 and 750, what does this indicate about the true mean?

The choice indicating that the true mean is between 300 and 750 is correct because a confidence interval provides a range of values within which we expect the true population mean to fall, given a specified level of confidence—in this case, 95%. Therefore, when a confidence interval is established between 300 and 750, it suggests that there is a high level of certainty (95%) that the true mean of the underlying population lies somewhere within this range.

The nature of confidence intervals implies that while it is possible for the true mean to fall outside this interval, the statistical evidence supports that it is most likely within the given limits, reinforcing the interpretation of the interval as a plausible range for the mean. This understanding is foundational in both statistics and data analysis, especially when making inferences about a population based on sample data.