Question

The total revenue in Rupees received from the sale of $x$ units of a product is given by
$R\left(x\right)=3x^2+36x+5$. The marginal revenue, when
$x=15$ is

• A. $90$
• B. $116$
• C. $126$
• D. $96$

Answer 1

The correct option is C $126$

We know, marginal revenue is the rate of change total revenue with respect to the number of items sold at an instant.
Let $M.R$. be marginal revenue, so

$M.R.=\frac{dR}{dx}$

It is given

$R\left(x\right)=3x^2+36x+5$

Now,

$M.R.=\frac{d}{dx}\left[R\right(x\left)\right]$

$\Rightarrow M.R.=\frac{d}{dx}[3x^2+36x+5]$

$\Rightarrow M.R.=6x+36$

When $x=15$, we get

$\Rightarrow M.R.=6\left(15\right)+36=126$

Hence, Correct answer is $\left(D\right)$