Respuesta :
key is "Tony is maximizing total utility"
4 max total utility,
marginal utility of DVD per $/DVD = marginal utility of water per $/gallon
if his marginal utility from water is 0.4 units per gallon, and pays $50 for 10,000 gallons of tap water,
marginal utility of water per $ = 0.4/(50/10000)=80
80 = marginal utility of DVD/6
marginal utility of DVD = 80*6
= 480 units per DVD
Cost per DVD is $6 each
Cost per gallon of tap water is $50/10000 = $0.005
In order to maximizing total utility for Tony:
The marginal utility of a DVD rental / cost per DVD
= The marginal utility of a gallon of water / cost per gallon
The marginal utility of a DVD rental
= The marginal utility of a gallon of water * 6 / 0.005
= 480 units per DVD