Assume the demand for good X is log-linear, with a constant price elasticity of -½ {i.e., QX = c • (PX)-1/2}.
(a) If the quantity demanded is 80 when PX is $4.50, what is the quantity demanded when PX is $2.00?
(b) Using your answer in part (a), find the precise arc price elasticity between $2.00 and $