Solve
-Find Out How Long It Takes A $\$ 3100$ Investment to Double If It Is Invested At

Multiple Choice

Solve.
-Find out how long it takes a $\$ 3100$ investment to double if it is invested at $8 \%$ compounded semiannually. Round to the nearest tenth of a year. Use the formula $A = P \left( 1 + \frac { r } { n } \right) ^ { n t }$ .

A) $8.6$ years
B) 9 years
C) $9.2$ years
D) $8.8$ years