a) i. What is a demand function?

ii. How does it differ from a demand curve?

iii. Differentiate a change in demand and a change in quantity demanded. Use graphs to support your answer.

b) The annual demand for motorcycles in Kuala Langat district has been estimated by Huffy Sdn Bhd economists to be exponential:

QD= 0.34P-5.3I 0.9 A0.24Ps-0.77

where QD is the number of motorcycles sold in Kuala Langat, P is the average price of motorcycles, I am the disposable income in Kuala Langat, A is the amount of advertising is done by Huffy, and Ps is the average price of scooters.

i. Interpret the exponents of the independent variables.

ii. Do the signs of the exponents make economic sense to you? Which does not make sense?

iii. If Huffy expands its advertising budget by 3%, what is the anticipated percentage increase in Huffy sales in this district?