World wide annual sales of all cell phones are approximately

World wide annual sales of all cell phones are approximately -10p +1000 million when the wholesale price was at what wholesale price should cell phones have been sold to maximize annual income D= $. what would have been the resulting revenue? $ million

Solution

Sales of q moblie phones : q = -10p + 1600

p = (1600 -q)/10

Revenue, R(q) = q(1600 -q)/10 = -q^2/10 + q1600

maximum revenue occurs at vertex: q = -(1600/-2*10) = 160/2 = 80

price , p = (1600 -80)/10 = $152

Max. Revenue = 152*80 = $ 12160