Answer: $400
Explanation:
Marginal Revenue is the revenue that is added by one additional unit.
When the product was selling at $2,000 it sold 15 units meaning the total revenue was;
= 2,000 * 15
= $30,000
When the product started selling for $1,900 it would be able to sell 16 units so the total Revenue is;
= 16 * 1,900
= $30,400
The difference in total Revenue is as a result of 1 extra unit, the 16th unit which contributed an amount of;
= 30,400 - 30,000
= $400