Question

if the price falls from $200 to $150, what is the elasticity of demand over this range.
price.       quantity demanded
$200.      1000
   150.      1400
   100.      1800

Answer 1

Using percentage method:
Change in price = 150-200 = -50
% change in price = -50 / 200*100 = -25%
Change in demand =1400-1000= 400
% change in demand = 400 /1000 *100 = 40%
Price elassticity of demand = % change in demand / % change in price
		40% / -25% = - 1.6
Note: This can be measured through Mid point formula as well.
Change in price= -50
Average price (200+150) /2 = 175
% change in price = -50 /175 *100 = -28.57%
Change in demand = 400
Average demand = (1400+1000)/2 = 1200
% change in demand = 400 /1200*100 =33.33%
Price elassticity of demand = % change in demand / % change in price
			33.33% / -28.57% = -1.17