For the given cost function C(x)=250x+x21000\displaystyle {C}{\left({x}\right)}={250}\sqrt{{{x}}}+{\frac{{{x}^{{2}}}}{{{1000}}}} find
a) The cost at the production level 1300  
b) The average cost at the production level 1300  
c) The marginal cost at the production level 1300  
d) The production level that will minimize the average cost.  
e) The minimal average cost.  

Give answers to at least 3 decimal places.