In your own words, how do you define the concept of economics? Describe some economic activities that can help illustrate and further explain the concept of
economics. Elaborate on your definition by explaining the unique roles that goods
and services play in economic activities.

Consider a treasury bill with a rate of return of 5% and the following risky securities: security a: e(r) = .15; variance = .0400 security b: e(r) = .10; variance = .0225 security c: e(r) = .12; variance = .1000 security d: e(r) = .13; variance = .0625 the investor must develop a complete portfolio by combining the risk-free asset with one of the securities mentioned above. the security the investor should choose as part of her complete portfolio to achieve the best cal would be a. security a b. security b c. security c d. security d