The money to be spent for the welfare of the employees of a firm is proportional to the rate of change of its total revenue (Marginal Revenue). If the total revenue ( in rupees) received from the sale of x units of a product is given by

R(x) = 3 x2 + 36 x + 5, find the marginal revenue, when x = 5, and write which value does the question indicate.

Given: Marginal Revenue, M(x) =


M(x) proportional to Money spent on the welfare of employees.


Thus, M(x) = k (Money spent on the welfare of employees)


M(x) = 6 x + 36


At x = 5, M(x) = 66


Now at x = 6, M(x) = 72


Thus Marginal Revenue for x = 5 is 66


And when x increased from x = 5 to x = 6,


Marginal revenue also increases and thus the money spent on the welfare of employees increases.


10