Solve the following: : The relation between price $(P)$ and demand $(D)$ of a cup of Tea is given by $D=\frac{12}{P}$. Find the rate at which the demand changes when the price is ₹ $2 /-$. Interpret the result.
Solve the following examples: : The cost of producing $x$ articles is given by $C=x^2+15 x+81$. Find the average cost and marginal cost functions. Find marginal cost when $x=10$. Find $x$ for which the marginal cost equals the average cost.
Solve the following examples: : The total cost function of producing $n$ notebooks is given by $C=1500-75 n+2 n^2+\frac{n^3}{5}$ Find the marginal cost at $n=10$.