Toyota Corp's stock is $$35$ per share. Its expected return is $24\%$ and variance is $12\%.$ Honda Corp's stock is $$21$ per share. Its expected return is $15\%$ and variance is $4\%.$ Benz Corp's stock is $$42$ per share. Its expected return is $15\%$ and variance $5\%.$ The covariance between Toyota and Honda is $0\mathrm{.}06.$ What would be the standard deviation of a portfolio consisting of $50\%$ Toyota and $50\%$ Honda?