Smooth Sailing, Inc., has estimated the demand function for its sailboats (quantity purchased annually) as follows:

Where,

Q_D = quantity purchased,

P_S = the price of smooth sailing sailboats,

P_X = the price of Company X's sailboat,

P_Y = the price of Company Y's motorboat,

I = per capita income in dollars,

A = dollars spent on advertising, and

W = number of favorable days of weather in the southern region of the United States.

a)Suppose that P_S = $9,000, P_X = $9,500, P_Y = $10,000, I = $15,000, A = $170,000, and W = 160. Find the price elasticity of demand at that point.

b)Is Elasticity of demand is elastic, inelastic, or unitary elastic in part (a)? Justify?