Toyota Corp's stock is $$25$ per share. Its expected return is $23\%$ and variance is $15\%.$ Honda Corp's stock is $$23$ per share. Its expected return is $19\%$ and variance is $5\%.$ Benz Corp's stock is $$48$ per share. Its expected return is $12\%$ and variance $6\%.$ The covariance between Toyota and Honda is $0\mathrm{.}05.$ What would be the standard deviation of a portfolio consisting of $50\%$ Toyota and $50\%$ Honda?