"Twelve sheep were fed a special diet consisting of dried grass and barley for three 2. months. At the end of the period the plasma insulin concentration (U/ml) was determined for each sheep. The data are as follows:20.5 26.2 18.8 21.2 22.1 21.6 25.4 26.8 22.9 22.8 30.8 28.4 Calculate the following:a) First (Q1) and third (Q3) quartiles, b) The interquartile range (IQR). "