At an Oregon fiber-manufacturing facility, an analyst estimates that the weekly number of pounds of acetate fibers that can be produced is given by the function :
z=f(x,y)=1250ln(yx^2)+45(y^2+x)(x^3 -2y)-(xy)^1/2
where
z= the weekly # of pounds of acetate fiber produced
x=the # of skilled workers at the plant
y= the # of unskilled workers at the plant
b) A week later, 20 skilled workers and 12 unskilled workers are employed due to the increasing demand of acetate fiber. What is the rate of change of output with respect to skilled worker?