Answer: A.) 4
Step-by-step explanation: Order the Heights given from least to greatest, this would be 67,72,72,73,76,76,76,76,78,84 . From here find the median of the data set by counting off evenly on both sides of the data set until you get to the middle number, or in this case, middle number(s). You will be left with two 76 inch values and you must take the average of these
to numbers (76 + 76 = 152 152 / 2 = 76) once you take the average of those two numbers you are left with 76, which is the median and 2nd quartile. Mark this number and then move to the left of this 76, and you will repeat the process of finding the median, leaving you with 72, this marks your first quartile aka "upper quartile". Return to the original median which was 76, and move to the number right of it and begin the median finding process once again, you're left with 76 again. Finally, with this information known you can find the IQR (interquartile range) of the data set. Subtract the 3rd quartile value, which is 76, from the first quartile value, which is 72 (Q3 - Q1 = IQR) (76 - 72 = 4). This leaves you with a value of 4 as you IQR.