a =  income value at the lower limit of the category containing the median  
b =  income value at the upper limit of the category containing the median  
P_{a} =  proportion of the distribution that lies below the lower limit  
P_{b} =  proportion of the distribution that lies below the upper limit 
Through basic algebraic transformations, we use these known values to solve for k and theta as shown in Figures 4 and 5. The median can then be calculated by inserting the values of k and theta into the formula in Figure 1.
Figure 2: Proportion below lower limit  Figure 3: Proportion below upper limit  
