Consider an economy with two types of firms, $S$ and I. $S$ firms all move together. I firms move independently. For both types of firms, there is a $64\%$ probability that the firm will have

a $25\%$ return and a $36\%$ probability that the firm will have a $-2\%$ return. What is the volatility $($standard deviation$)$ of a portfolio that consists of an equal investment in:

a$.40$ firms of type $S?$

b$.40$ firms of type I?

a$.$ What is the volatility $($standard deviation$)$ of a portfolio that consists of an equal investment in $40$ firms of type S$?$

Standard deviation is

$\%.($Round to two decimal places.$)$