Sample Answer: Eight years. To get ½ of the 300, you need 0.5^(t/8) to equal ½, or 0.5. That means that the exponent must be 1. This happens when t = 8 years. Check all facts you included in your answer. The exponential part of the expression needs to be equal to ½, or 0.5. The half-life time will occur at the value of t that gives an exponent of 1. The value t = 8 causes the exponent to be 1, so that’s the half-life.