notes/Areas/upv/classes/empresario/07a-Price-Elasticity.md

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2022-06-05 18:53:01 +02:00
# Price Elasticity
We can calculate how our projected profits change when increasing or decreasing the price of our product.
$|E_d| = \frac{\Delta Q(\%)}{\Delta p(\%)}$
If $E_d > 1$ the price is **elastic**, when $E_d < 1$ the price is **inelastic** and when $E_d = 1$ the price is **unitary**.
If we break the formula down, it is basically % Change in Quantity / % Change in price.
**Example:**
You sell 10.000 reams of paper at 100€/ream, you raise the price to 150€/ream and sell 7.000 reams.
The Price Elasticity is now $\displaystyle \frac{\frac{QN-QI}{(QN+QI)/2}}{\frac{PN-PI}{(PN+PI)/2}}$
$QN$= old Quantity
$QI$= new Quantity
$PN$= old Price
$PI$= new Price
So when we replace the variables with our numbers we get:
$\displaystyle E_d = \frac{\frac{10000-7000}{(10000+7000)/2}}{\frac{100-150}{(100+150)/2}}$
$\displaystyle E_d \approx 0.88$
This means the price is inelastic. Meaning changes in price result in small changes to demand.
**Moar Examples:**
At a price of € 4 the quantity demanded of a particular good is
100 units.
1. Calculate the value of the price elasticity.
2. Explain what type of demand.
3. Plot the elasticity of demand
In each case:
a) If the price increases to 5 € and quantity demanded decreases to 90 units.
b) If the price increases to 5 € and quantity demanded decreases to 50 units.
c) If the price increases to 5 € and quantity demanded decreases to 75 units.
d) If the price increases to 5 € and quantity demanded remains unchanged.
e) If the price stays the same and the quantity demanded increases by 10 units.
$\displaystyle a = \frac{\frac{100-90}{(100+90)/2}}{\frac{4-5}{(4+5)/2}} \approx -0.47$
**Inelastic**
$\displaystyle b = \frac{\frac{100-50}{(100+50)/2}}{\frac{4-5}{(4+5)/2}} = -3$
**Elastic**
$\displaystyle c = \frac{\frac{100-75}{(100+75)/2}}{\frac{4-5}{(4+5)/2}} \approx -1.28$
**Elastic**
$\displaystyle d = 0$
**Perfectly Inelastic**
$\displaystyle e = \frac{(100-110)/((100+110)/2)}{(4-4)/((4+4)/2)} = -\frac{2}{0} = Infinity$
**Perfectly Elastic**
**Example 3:**
ppu = 30
quantity = 300
new ppu = 45
new quantity = 225
$\displaystyle E_d = \frac{(300-225)/((300+225)/2)}{(30-45)/((30+45)/2)} \approx |-0.71|$
**Inelastic**