Final answer:
The critical percentage value refers to specific points in a distribution that determine ranges where a specified percentage of data lies, often used in statistical analysis to describe aspects like percentile ranks or confidence interval bounds.
Step-by-step explanation:
The critical percentage value in a statistical context typically refers to the value above or below which a certain percentage of data in a distribution falls. For instance, the 90th percentile k is a critical value where 90 percent of the data is the same or lower, and 10 percent is the same or higher than k. Similarly, in normal distribution, the z-score of 1.645 as a critical value means that to capture the central 90 percent of the distribution, 1.645 standard deviations are considered on either side of the mean. Calculating percents involves expressing a fractional amount out of 100, as in the case where the percentage value is a way of expressing rates such as yield, endangered species, or student positivity rates.