Practice Problem $13-$ Diversification using Different Types of Stocks

Stocks within a single industry tend to have a higher correlation than stocks in different industries.

Likewise, stocks in different countries have lower correlation on average than stocks within the

United States.

What is the volatility of a very large portfolio of stocks within an industry in which the stocks have a

volatility of $40\%$ and a correlation of $60\%?$ What is the volatility of a very large portfolio of

international stocks with a volatility of $40\%$ and a correlation of $10\%?$