<p>Revenue and marginal revenue are defined as a function of <span class="math-container">$Q$</span>, not of the price. If <span class="math-container">$Q=10000$</span> is the maximal demand (assuming consumers have unit demand), then an additional unit produced will be left unsold, so total revenue becomes constant and marginal revenue drops to zero at <span class="math-container">$Q=10000$</span>.</p>

CC BY-SA 4.0
2023-04-28T14:13:31.987Z
If the change in $Q$ is zero, but the total revenue is still changing then expression above, which is essentially just a derivative without limit, could not possibly be zero.
Chris
CC BY-SA 4.0
2023-04-29T15:21:26.093Z
@Chris If you produce one more unit, then the change in $Q$ is not zero, it is $1$.
VARulle
CC BY-SA 4.0
2023-04-29T18:22:06.393Z
My point is that the total revenue is changing but the production is not
Chris
CC BY-SA 4.0
2023-04-29T18:41:04.727Z
@Chris But $\Delta TR$ and $\Delta Q$ are not changes induced by an exogenous price change. Rather, the change in  revenue is induced by the exogenous change in $Q$.
VARulle
CC BY-SA 4.0
2023-04-28T09:08:16.700Z
2023-04-28T09:08:16.700Z
VARulle
<p>The marginal revenue is defined (at least in my Econ 101 course) as <span class="math-container">$\Delta TR/\Delta Q$</span>. However, say I am examining a town with <span class="math-container">$10,000$</span> people, and at a nonzero certain price, <span class="math-container">$10,000$</span> people demand a product. Decreasing the price decreases total revenue since there is no change in quantity, but what happens to marginal revenue? It seems to be ill defined in this case.</p>

<microeconomics><marginal>
What happens to marginal revenue when quantity does not change?
Chris
# What happens to marginal revenue when quantity does not change?

(Asked by: username_0 on 2023-04-28)

The marginal revenue is defined (at least in my Econ 101 course) as $\Delta TR/\Delta Q$. However, say I am examining a town with $10,000$ people, and at a nonzero certain price, $10,000$ people demand a product. Decreasing the price decreases total revenue since there is no change in quantity, but what happens to marginal revenue? It seems to be ill defined in this case.

**Tags:** microeconomics, marginal

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## 1 answers

### Answer by username_1 on 2023-04-28. Score: 1

Revenue and marginal revenue are defined as a function of $Q$, not of the price. If $Q=10000$ is the maximal demand (assuming consumers have unit demand), then an additional unit produced will be left unsold, so total revenue becomes constant and marginal revenue drops to zero at $Q=10000$.

> **Comments:**
> **username_0**: If the change in $Q$ is zero, but the total revenue is still changing then expression above, which is essentially just a derivative without limit, could not possibly be zero.  
> **username_1**: @Chris If you produce one more unit, then the change in $Q$ is not zero, it is $1$.  
> **username_0**: My point is that the total revenue is changing but the production is not  
> **username_1**: @Chris But $\Delta TR$ and $\Delta Q$ are not changes induced by an exogenous price change. Rather, the change in  revenue is induced by the exogenous change in $Q$.  

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