QPaperGen

The total revenue (in rupees) from selling \(x\) units of a product is given by:
\[R(x) = 3x^2 + 36x + 5\]

We are asked to find the marginal revenue when \(x = 15\).\[\]

Marginal revenue is the rate of change of total revenue with respect to the number of units sold:

\[\therefore MR = \dfrac{dR}{dx} = 3 \cdot 2x + 36 = 6x + 36\]

Substituting \(x = 15\):

\[MR = 6 \cdot 15 + 36 = 90 + 36 = 126\]

Final Answer:
The marginal revenue when \(x = 15\) is Rs. 126.