Question

the pressure exerted on the floor by the heel of someone's shoe is inversely proportional to the square of the width of the heel of their shoe. When Megumi wears 2cm wide heels, she exerts a pressure of 400 kPa. Determine a function to represent the pressure, p, exerted by Megumi if she wears heels of width, w.

Answer 1

P = k/w^2 

first of all you need to find k 
But I kind of don't like the units of each value so let say 
400KPa = 4 * 10^5 Pa = 4 * 10^5 N/m^2 
2 cm = 2 * 10^-2 m 

input values in the equation 

4*10^5 = k/(4*10^-4) >>> k = 160 N 

P = 160/w^2 
it said if she wears a heel with a width of .5 cm 

P = 160(0.5 * 10^-2)^2 >>> P = 6400 KPa