Developed by Nobel Laureate Harry Markowitz, modern portfolio theory is a widely used investing model designed to help investors minimize risk while maximizing returns for their portfolio. The Markowitz efficient frontier is a set of portfolios with returns that are maximized for a given level of risk.

This question tests your understanding of efficient vs inefficient investments. Consider the following risky portfolios:

Portfolio	Expected Return	Standard Deviation
Q	10.0%	15.0%
R	10.5%	16.5%
S	11.5%	18.5%

Which of these portfolios cannot be on the Markowitz efficient frontier of risky assets (i.e. without the risk-free asset)? Explain briefly.