If an investor decides on the all-Microsoft portfolio (in the text example), does it make sense to use the Sharpe ratio to decide whether to invest $2,000 or $4,000? If the correlation between the...

If an investor decides on the all-Microsoft portfolio (in the text example), does it make sense to use the Sharpe ratio to decide whether to invest $2,000 or $4,000?

If the correlation between the price of Microsoft stock and the price of an Xbox is 1, could you predict the price of an Xbox from knowing the price of Microsoft stock? How well?