Arational decision maker takes an action if and only if

A rational decision maker takes action if and only if the marginal benefit of the action exceeds the marginal cost.    

Explanation:

Rational people always think at the margin. Decision makers generally consider both the explicit and implicit costs of their actions.

The decision-making is the process of making choices in the optimal level of benefit or utility for an individual. Rational decision making is a multi-step process that makes choices between the alternatives.

A rational decision maker takes action if and only if the marginal benefit of the action exceeds the marginal cost.

they encountered severe weather for which they were poorly prepared.

for many centuries there were important factors which the economies of the muslim empires developed increasingly. they applied economic procedures in production, investment, finance, taxation and property. they used to tax certain goods (for example: harvest), they charged interest on money lent, they signed contracts with merchants; they relied on a common currency, and they used checks as well as promissory notes. with the money collected by means of taxation, the government provided the needy with an income. in addition, trading networks covered huge distances, so far regions started to have contact and exchange goods. this trade network covered areas of asia, africa and europe.