The marginal revenue is $MR = 100 - 2x$ rupees. By how much does total revenue rise when sales go up from 10 to 20 units?

Explanation

1. 01

   $\int_{10}^{20} (100 - 2x)\,dx = \left[100x - x^{2}\right]_{10}^{20}$.

2. 02

   $= (2{,}000 - 400) - (1{,}000 - 100) = 700$ rupees.