So, the basic formula for calculating marginal revenue is As a simplified example, let's say that Apple can sell 10 iPhones if it charges $700. If Apple decides to lower the price to $680, it can ...

You can plot your marginal revenue curve on the same graph as your demand curve. For 11 sales, the demand curve shows a price of $4.95 – but the marginal revenue from that 11th sale is $4.45.