<span>In statistics finding percentiles relates to the standard deviation and something called a z-score. For normally distributed data the z-score represents how many standard deviations above or below the mean that group is a part of. The z-score for normally distributed data for the 90th percentile is 1.28. The standard deviation is then multiplied by the z-score to find, in this case, the shotlrtest height needed to be in the 90th percentile of this population. In this case to be in the 90th percentile your height must be 60.27 inches.</span>
The interquartile range is from Q1 to Q3 and to get this you have to subtract Q2 by Q3. The 10 units represent that only 10 units are fit in the given range.