Demand and Revenues for a Monopoly

\begin{tabular}{|l|l|l|l|}
\hline
Price (dollars) & Quantity (units) & Total Revenue (dollars) & Marginal Revenue (dollars) \\
\hline
\[tex]$40 & 0 & & \\
\hline
\$[/tex]35 & 5 & & \\
\hline
\[tex]$30 & 10 & & \\
\hline
\$[/tex]25 & 15 & & \\
\hline
\[tex]$20 & 20 & & \\
\hline
\$[/tex]15 & 25 & & \\
\hline
\end{tabular}

Using the demand schedule, what is the marginal revenue (MR) for the [tex]\(10^{\text{th}}\)[/tex] unit?



Answer :

Sure! Let's break down how to find the marginal revenue (MR) for the 10th unit step-by-step.

### Step 1: Calculate Total Revenue
Total Revenue (TR) is calculated by multiplying the price (P) by the quantity (Q) for each row in the table.

Using the given prices and quantities:

1. [tex]\( P = \$40 \)[/tex] and [tex]\( Q = 0 \)[/tex]:
[tex]\[ TR = 40 \times 0 = 0 \][/tex]
2. [tex]\( P = \$35 \)[/tex] and [tex]\( Q = 5 \)[/tex]:
[tex]\[ TR = 35 \times 5 = 175 \][/tex]
3. [tex]\( P = \$30 \)[/tex] and [tex]\( Q = 10 \)[/tex]:
[tex]\[ TR = 30 \times 10 = 300 \][/tex]
4. [tex]\( P = \$25 \)[/tex] and [tex]\( Q = 15 \)[/tex]:
[tex]\[ TR = 25 \times 15 = 375 \][/tex]
5. [tex]\( P = \$20 \)[/tex] and [tex]\( Q = 20 \)[/tex]:
[tex]\[ TR = 20 \times 20 = 400 \][/tex]
6. [tex]\( P = \$15 \)[/tex] and [tex]\( Q = 25 \)[/tex]:
[tex]\[ TR = 15 \times 25 = 375 \][/tex]

The Total Revenues are: [tex]\([0, 175, 300, 375, 400, 375]\)[/tex].

### Step 2: Calculate Marginal Revenue
Marginal Revenue (MR) is calculated as the change in Total Revenue divided by the change in Quantity.

1. For the quantity between 0 and 5 units:
[tex]\[ MR = \frac{175 - 0}{5 - 0} = \frac{175}{5} = 35 \][/tex]
2. For the quantity between 5 and 10 units:
[tex]\[ MR = \frac{300 - 175}{10 - 5} = \frac{125}{5} = 25 \][/tex]
3. For the quantity between 10 and 15 units:
[tex]\[ MR = \frac{375 - 300}{15 - 10} = \frac{75}{5} = 15 \][/tex]
4. For the quantity between 15 and 20 units:
[tex]\[ MR = \frac{400 - 375}{20 - 15} = \frac{25}{5} = 5 \][/tex]
5. For the quantity between 20 and 25 units:
[tex]\[ MR = \frac{375 - 400}{25 - 20} = \frac{-25}{5} = -5 \][/tex]

The Marginal Revenues are: [tex]\([35, 25, 15, 5, -5]\)[/tex].

### Step 3: Determine the Marginal Revenue for the 10th unit
To find the MR for the 10th unit, we look at the interval between 5 and 10 units, which gives us the second MR value:

[tex]\[ MR \text{ for the 10th unit} = 25 \][/tex]

So the marginal revenue for the 10th unit is $25.