Chapter 4: Problem 27
For each demand function \(D(p)\) : a. Find the elasticity of demand \(E(p)\). b. Determine whether the demand is elastic, inelastic, or unit-elastic at the given price \(p\). $$ D(p)=4000 e^{-0.01 p}, \quad p=200 $$
Short Answer
Expert verified
The demand is elastic with \(E(200) = -2\).
Step by step solution
01
Write the formula for elasticity of demand
The elasticity of demand with respect to price, \(E(p)\), is given by the formula: \[E(p) = \frac{D'(p) \times p}{D(p)}\]where \(D'(p)\) is the derivative of the demand function.
02
Differentiate the demand function
Given the demand function \(D(p) = 4000 e^{-0.01p}\), we need to find \(D'(p)\). Using the chain rule, the derivative is:\[D'(p) = \frac{d}{dp} [4000 e^{-0.01p}] = 4000 \cdot (-0.01) \cdot e^{-0.01p} = -40 e^{-0.01p}\]
03
Substitute the derivative and demand function into the elasticity formula
Plug the derivative \(D'(p) = -40 e^{-0.01p}\), \(D(p) = 4000 e^{-0.01p}\), and \(p = 200\) into the elasticity formula:\[E(200) = \frac{-40 e^{-0.01 \times 200} \times 200}{4000 e^{-0.01 \times 200}}\]Simplify the expression to:\[E(200) = \frac{-8000 e^{-2}}{4000 e^{-2}} = -2\]
04
Interpret the elasticity value
The elasticity \(E(200) = -2\) indicates that the demand is elastic. In economic terms, if the absolute value of elasticity is greater than 1, the demand is considered elastic.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Understanding the Demand Function
A demand function represents the relationship between the price of a product and the quantity demanded by consumers. It's typically expressed as a mathematical equation. For instance, in the given exercise, the demand function is \(D(p) = 4000 e^{-0.01p}\). This tells us that the quantity demanded decreases exponentially as the price \(p\) increases.
- The function involves an exponential term \(e^{-0.01p}\), highlighting how demands diminish with rising prices.
- An essential aspect of understanding demand functions is how they capture consumer behavior in response to price changes.
Derivatives in Calculus for Economic Analysis
Derivatives play a crucial role in economic analysis, especially when it comes to understanding changes in demand with respect to price. The derivative of a function provides the rate at which the function's value changes with respect to a change in its input. In the context of demand functions:
- The derivative \(D'(p)\) indicates how the quantity demanded changes as the price changes.
- Using calculus, we differentiate the given demand function \(D(p) = 4000 e^{-0.01p}\) and find \(D'(p) = -40 e^{-0.01p}\).
Exploring Economic Elasticity
Economic elasticity measures how responsive the quantity demanded is to changes in price. The elasticity of demand, specifically, helps us understand whether a demand curve is more flexible or stiff:
- If demand is elastic, consumers significantly change their quantity demanded when prices change (elasticity absolute value is greater than 1).
- If demand is inelastic, the changes in price don't greatly affect the quantity demanded (elasticity absolute value is less than 1).
- If the demand is unit-elastic, the percentage change in quantity demanded is equal to the percentage change in price (elasticity absolute value is 1).
Applying the Chain Rule in Calculus
The chain rule is a fundamental tool in calculus used to differentiate composite functions. In this exercise, it's used to find the derivative of the demand function, which includes an exponential component:
- The demand function \(D(p) = 4000 e^{-0.01p}\) contains two parts: a constant (4000) and an exponential term \(e^{-0.01p}\).
- To differentiate, the chain rule helps us "unlink" these parts, allowing us to take the derivative of the outer function along with the derivative of the inner function.