EC 110 Lecture Notes - Lecture 4: Normal Good

1. Assume a monopoly has the following demand schedule:

Price (P) Quantity (Q)

$20            200

15              300

10              500

5                700

(a) Calculate total revenue (TR) at each P and Q combination.

(b) Calculate marginal revenue per unit for each decrease in price.

(c) For the change in price from $20 to $15, calculate the interval elasticity of demand. Is demand elastic or inelastic?

(d) For the change in price from $20 to $15, obtain the Lerner index.

Use the following demand schedule for a monopolist to calculate total revenue and marginal revenue. For each price, indicate whether the demand is elastic, unit elastistic or inelastic. Using the data from the demand schedule,graph the demand curve, the marginal revenue curve and the total revenue curve. Identify the elastic, unit elastic and inelastic segments along the demand curve.

Price(P)	Quantitiy demanded (Q)	Total Renenue (TR)	Marginal Revenue (MR)	Price elasticity of demand
5	0
4.5	1
4	2
3.5	3
3	4
2.5	5
2	6
1.5	7
1	8
0.5	9
0	10

From the scenario for Katrina’s Candies, examine the procedure Herb will use to estimate the "demand model" for this product and comment on the expected price elasticity, income elasticity, and cross price elasticity of demand. That is, do you expect demand to be price elastic or inelastic? Will the income elasticity suggest Katrina Candies is a luxury or a necessary good? And, is there likely to be a strong cross price elasticity with the other products that Herb included in his demand model? Explain your answers. What can you determine about consumer demand for a product whose estimated demand elasticities are as follows: Price Elasticity of demand is -0.85 Income Elasticity of demand is 2.5 Cross Price Elasticity of demand with this product and your product is -2 I would like you to think about this simple formula for predicting the change in total revenue when there is a given percentage change in price. Using the example above, if ED (price elasticity of demand) is -.85, then a 10% increase in price will cause the quantity demanded to fall by 8.5%, (-8.5% / 10% = -.85). The Formula for Predicting % Changes in Total Revenue is: %ΔTR = %ΔQ + %ΔP where TR = Total Revenue, Q is Quantity Demanded and P = price. Using this formula, what would be the % Δ in TR if ED is -.85 and the %ΔP is 10%?