Here is a simple online outlier boundary calculator which is used to find lower and upper class boundaries from the given set of numbers. A set with an upper bound is said to be bounded from above by that bound, a set with a lower bound is said to be bounded from below by that bound. In the below Outlier calculator, just enter the list of numbers separated by comma and click calculate. You get the first, third quartiles, median, lower and upper boundaries for the given list.
Find the Inter-quartile by the number series of 1,2,5,3,11,9,10,15.
First Quartile (Q1): 2.5
Third Quartile (Q3): 10.5
Inter-quartile Range (IQR) = Q3 - Q1
IQR = 10.5 - 2.5
IQR = 8
Lower Outlier Boundary = Q1 - 1.5 * IQR
LQB = 2.5 - 1.5 * 8
LQB = No boundaries at lower end
Upper Outlier Boundary = Q3 + 1.5 * IQR
UQB = 10.5 + 1.5 * 8
UQB = 22.5