A) Price Elasticity Of Demand - It is the percentage change in quantity demanded divided by the percentage change in price.

Calculated as = %change in quantity demanded/%change in price

i) Point B to Point C

% change in Quantity demanded = (-200/8800)*100 = -2.27

% change in price = (10/190)*100 = 5.2

Price Elasticity Of Demand from point B to C = %change in quantity demanded/%change in price

= -2.27/5.2

= -0.43

ii) Point G to Point H

% change in Quantity demanded = (-200/7800)*100 = -2.5

% change in price = (10/240)*100 = 4.1

Price Elasticity Of Demand from point B to C = %change in quantity demanded/%change in price

= -2.5/4.1

= -0.6

B) Price Elasticity Of Demand For The Following:

i) Gold Watch - Price elasticity of demand for a gold watch will be elastic because it has many close substitutes example watches made up of different materials. Also, due to a large proportion of income spent on the gold watch, with the increase in price its demand will fall, hence elastic demand.

ii) Nasal Decongestant Spray - Price elasticity of demand for Nasal Decongestant Spray will inelastic because of lack of close substitutes, Small proportion of income spent on it and single-use it can be put to.

iii) Food - The demand for basic food commodities is inelastic because it is a necessity of life. Basic food commodities have no close substitute and are put to a single use of satisfying hunger.

iv) Petrol from a particular gas station - The price elasticity of demand for petrol from a particular gas station will be elastic because of the availability of many close substitutes. With a hike in petrol price by the particular gas station, the consumers will shift their demand to other gas stations.

v) Petrol over the period of a week - Price elasticity of demand for petrol over the period of a week will be relatively less elastic as with the hike in petrol prices consumers will shift to a closer substitute such as kerosene, diesel, etc and switch to public transports, etc.

vi) Instructor's assigned textbook -  Price elasticity of demand for the instructor's assigned textbook will be inelastic due to the absence of a close substitute.