Answer:
The opportunity cost of lending the money to the friend is the largest expected return that could be earned with the money loaned to the friend. From the available opportunity, the investor could earn maximum of 40% by investing in oil well venture. Thus, the opportunity cost to the investor is 40%
The opportunity cost in dollar = Investment * Opportunity cost in %
= $5,000 * 40%
= $2,000
Thus, the opportunity cost in dollar is $2,000