At a price of $90 per month, there are 50,000 subscribers to Venture Cable-vision Service. If Venture were to reduce the price to $80 per month, the number of subscribers would increase to 70,000. Using the traditional method of calculating percentage change (and not the mid-point method), what is the price elasticity of demand for Venture cable television service?

a. 0.28

b. 1.0

c. 1.2

d. 1.5

e. 0.36

Why is the answer 0.36?