Here, we want to calculate the interquartile range
Mathematically, this is the difference between the lower quartile (1st quartile or 25th percentile) and the upper quartile (3rd quartile or 75th percentile)
We already have the numbers arranged from top to bottom
The count of numbers is 9 numbers
We have the first quartile as;
The third term here is the weight of baby Selena
The 3rd quartile can be calculated as;
The 8th term is the weight of baby Me
The difference between these weights give the interquartile range as follows;