4.2. Revenue

A firm earns revenue by selling the good that it produces in the market. Let the market price of a unit of the good be p. Let q be the quantity of the good produced, and therefore sold, by the firm at price p. Then, total revenue (TR) of the firm is defined as the market price of the good (p) multiplied by the firm’s output (q). Hence, TR = p × q

Total Revenue (TR) is calculated by multiplying the price per unit (p) by the quantity sold (q). This means that if a firm knows how much it can sell (q) and the price of each unit (p), it can find out its total revenue. For example, if a firm sells 5 units of a product at a price of 10 currency units each, their total revenue will be 5 * 10 = 50 currency units.

Think of a lemonade stand: if you charge $2 per cup and sell 5 cups in a day, your total revenue is 2 * 5 =$10. The same principle applies when calculating total revenue for any business.

Consider the following numerical example. Let the market for candles be perfectly competitive and let the market price of a box of candles be Rs 10. For a candle manufacturer, Total Revenue Table shows how total revenue is related to output:

Boxes sold | TR (in Rs) 0 | 0 1 | 10 2 | 20 3 | 30 4 | 40 5 | 50

This table illustrates how the total revenue increases as more boxes of candles are sold. When no boxes are sold, total revenue is zero. If 1 box is sold, total revenue equals Rs 10. If 2 boxes are sold, total revenue is Rs 20, continuing in this pattern. Essentially, the revenue doubles as the output doubles, showing a direct relationship between the quantity sold and total revenue.

Imagine you're at a local market selling oranges. If you sell 0 oranges, you earn nothing. If you sell 1 orange for $2, you earn$2. If you sell 5 oranges, you earn $10. This straightforward relationship helps you understand how to maximize your earnings.

We can depict how the total revenue changes as the quantity sold changes through a Total Revenue Curve. A total revenue curve plots the quantity sold or output on the X-axis and the Revenue earned on the Y-axis. Figure 4.1 shows the total revenue curve of a firm. Three TR observations are relevant here. First, when the output is zero, the total revenue of the firm is also zero. Therefore, the TR curve passes through point O. Second, the total revenue increases as the output goes up. Moreover, the equation ‘TR = p × q’ is that of a straight line because p is constant. This means that the TR curve is an upward rising straight line.

The Total Revenue Curve visually represents how the revenue generated by a firm changes as it sells more units of its product. When output is zero (the firm isn't selling anything), the total revenue is also zero. However, as the firm sells more, represented by the straight line on the graph, total revenue increases steadily because the price (p) remains constant. This linear relationship makes it easy to understand how sales volume directly impacts revenue.

Visualize a straight path going uphill. The steeper it is (representing higher prices), the quicker you reach a higher total revenue as you sell more products. Just as climbing a hill gets you to a better view (or more revenue), selling more units gets you more money!

The average revenue (AR) of a firm is defined as total revenue per unit of output. Recall that if a firm’s output is q and the market price is p, then TR equals p × q. Hence AR = TR/q = p/q = p. In other words, for a price-taking firm, average revenue equals the market price.

Average Revenue (AR) gives an idea of how much revenue a firm is making per unit sold. It’s calculated by dividing total revenue (TR) by the total quantity (q) produced. For firms in a perfectly competitive market, since they are price takers, the average revenue they earn per unit is equal to the market price. This relationship reinforces the direct linkage between market dynamics and individual firm performance.

Think about a pizza shop. If the shop earns $100 by selling 10 pizzas, the average revenue is$100/10 = $10 per pizza, which is also the selling price. It’s a straightforward way to see how much each sale contributes to overall earnings.

The marginal revenue (MR) of a firm is defined as the increase in total revenue for a unit increase in the firm’s output. Consider again the total revenue from the sale of 2 boxes of candles is Rs 20. Total revenue from the sale of 3 boxes of candles is Rs 30. Therefore, MR = Change in total revenue / Change in quantity = (30 - 20) / (3 - 2) = Rs 10

Marginal Revenue (MR) is important because it tells a firm how much additional revenue it earns from selling one more unit of product. In our example, if selling an extra box of candles increases revenue by Rs 10, that means each additional sale contributes Rs 10 to the firm’s earnings. This helps firms decide the optimal number of units to produce.

Imagine a fruit vendor. If selling an extra basket of strawberries brings in $5, that$5 is your MR. Understanding MR helps the vendor determine how many baskets to bring to the market each day: more baskets mean more potential earnings if the market demand exists!

Is it a coincidence that this is the same as the price? Actually it is not. For the perfectly competitive firm, MR=AR=p. In other words, for a price-taking firm, marginal revenue equals the market price.

In a perfectly competitive market, the marginal revenue earned from selling an additional unit of a good is always equal to the market price. This equality happens because each unit is sold at the same price, resulting in a stable relationship between marginal revenue and average revenue, which are both equal to the market price.

If you're selling lemonade for $1 a cup, each extra cup you sell brings exactly$1 in additional revenue. Whether you sell 1 cup or 10, every cup sold still has that same price, illustrating how marginal revenue consistently aligns with the market price.

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