Question

A(t)=934(1/2)t/30 for 20 years and 100 years

Answer 1

`\bf A(t)=934\left( (1)/(2) \right)^{(t)/(30)}\qquad \qquad \stackrel{t=20}{A(t)=934\left( (1)/(2) \right)^{(20)/(30)}\implies A(t)=934\left( (1)/(2) \right)^{(2)/(3)}} \\\\\\ \stackrel{t=100}{A(t)=934\left( (1)/(2) \right)^{(100)/(30)}\implies A(t)=934\left( (1)/(2) \right)^{(10)/(3)}}`

nothing to it, t = year, and you can just plug that in your calculator.