The demand function is $p = \frac{18}{x + 1}$, and the market sells 2 units. What is the consumer surplus?

Explanation

1. 01

   At $x_0 = 2$, $p_0 = \frac{18}{3} = 6$, so consumers pay $6 \times 2 = 12$.

2. 02

   $CS = \int_0^{2} \frac{18}{x + 1}\,dx - 12 = 18\log 3 - 12 \approx 7.78$ rupees.