I am given two equations:

Min 5K + 15L

and the constraint: 10=$\displaystyle L^{.5}K^{.5}$

given that K=4 (then L=25)

and am asked to find the:

1. short run average cost

2. short run variable cost

3. short-run marginal cost

And I'm a bit confused. What is the 10 actually represent in constraint? Is it total quantity produced?

Is the answer to question 1 suppose to be:

5(4) + 15(25)= 20+ 375= 395

395/10 = 39.5?

2. seems to be the cost of labor (wL), or in this case 15L, or w=15.

3. I know that SRMC should be the change in SRTC/ change in quantity. I just don't understand where your find those values.