Suppose that the price of a commodity increases from ₹ 90 to ₹ 110 and

Suppose that the price of a commodity increases from ₹ 90 to ₹ 110 and the demand curve shows that the corresponding reduction in quantity demanded is from 240 units to 160 units. Then, the coefficient of the price elasticity of demand will be

1·0
2·4
0·5
2·0
This question was previously asked in
UPSC CAPF – 2019
To calculate the coefficient of price elasticity of demand, we can use the midpoint formula which is suitable for discrete changes:
PED = |(Q2 – Q1) / ((Q1 + Q2) / 2)| / |(P2 – P1) / ((P1 + P2) / 2)|
Given:
P1 = ₹ 90, Q1 = 240 units
P2 = ₹ 110, Q2 = 160 units
Change in Q = Q2 – Q1 = 160 – 240 = -80
Change in P = P2 – P1 = 110 – 90 = 20
Midpoint Q = (Q1 + Q2) / 2 = (240 + 160) / 2 = 400 / 2 = 200
Midpoint P = (P1 + P2) / 2 = (90 + 110) / 2 = 200 / 2 = 100
PED = |-80 / 200| / |20 / 100|
PED = |-(0.4)| / |(0.2)|
PED = 0.4 / 0.2
PED = 2.0
– The price elasticity of demand measures the responsiveness of quantity demanded to a price change.
– The formula for arc elasticity (midpoint method) is appropriate for calculating elasticity over a range of prices and quantities.
– The absolute value of the calculated elasticity is typically reported.
The resulting elasticity of 2.0 indicates that demand is elastic between these two price points, as the percentage change in quantity demanded (40%) is greater than the percentage change in price (20%).