La función de demanda para cierta marca de cartucho de inyección de tinta es la siguiente, donde  p  es el precio unitario en dólares y  x  es la cantidad demandada cada semana, medida en unidades de mil.

Calcule la elasticidad de la demanda cuando  x  =  5 .

4. (10 marks) Opad, the blockbuster product of Opple Inc., has a weekly demand q that declines with price p according to q = 1000 e-p/200 (a) Find the elasticity of demand e at the current price of $100. (b) Use the elasticity of demand to calculate the marginal revenue at the current price of $100. Simplify your answer to "calculator ready". (c) If the price is raised by 1%, use the elasticity to estimate the percentage decline in sales.

(c) If the price is $12 and increases by 4%, what is the percentage change in demand? (Hint: Use the price elasticity of demand to answer this question.) You may leave your answer in the simplest calculator-ready form you can find.

(b) Use the elasticity of demand to calculate the marginal revenue at the current price of $100. Simplify your answer to "calculator ready".