Quartiles and interquartile range worksheet (with solutions)

Hello! Thank you for your comment. There are two approaches to find the lower and the upper quartiles. You can use the median to divide the ordered data set into two halves. Then the lower quartile value is the median of the lower half of the data and the upper quartile value is the median of the upper half of the data. If in the lower half there is an even number of values, we need the mean of the middle two values to find the first quartile and similarly for the upper half. Alternatively you divide the number of terms in the set plus 1 by 4, say (8+1)/4=2.25, and find the number in this position (for 2.25 you take the second number and add 0.25 times the difference between the third and second number). I am using the first approach. I hope this helps.