Answer:36
Step-by-step explanation:
Marginal product is the additional product that is derived from using additional unit of input, in this example labour. If a firm produces 50 units of an output with 50 labour , if the labour level is increased to 51 and firm produce 51 units, the marginal product of the additional one worker introduced is the additional one unit of the product produced.
In the above question, since the additional worker will increase production by 36 units, that is the marginal product of it's addition.