The document shows how to calculate quartiles and the interquartile range from a cumulative frequency histogram. It finds the upper quartile to be 8, the lower quartile to be 5.5, and calculates the interquartile range as 8 - 5.5 = 2.5. It also finds the median to be 6.8 by multiplying the highest frequency by 2/1 and locating it on the cumulative frequency axis.