Taking a nap

All of these answers involve trade-offs.

Watching a football game on Saturday afternoon

Going to university

economical.

unlimited

efficient.

scarce

how society manages its unlimited resources.

how to reduce our wants until we are satisfied

how society manages its scarce resources

how to fully satisfy our unlimited wants

the action is ethical

the action produces marginal costs that exceed marginal benefits

the action produces marginal benefits that exceed marginal costs

the action makes money for the person

nothing, because you found the money

Rs.20 (because you could have used the Rs.20 to buy other things) plus the value of your time spent at the game

Rs.20 (because you could have used the Rs.20 to buy other things) plus the value of your time spent at the game, plus the cost of the dinner you purchased at the game

Rs.20 (because you could have used the Rs.20 to buy other things).