Answer:
The standard deviation of the portfolio is 26.15%
Explanation:
First the formula of variance of a portfolio is used.
Take the square root of variance to get standard deviation.
(0.3)^2 × (0.35)^2 + (0.7)^2 × (0.3)^2 + 2 × 0.3 × 0.7 × 0.35 × 0.3 × 0.3 = 0.068355
Taking square root of 0.068355 to get standard deviation that is 26.15%
