An archaeologist locates a fossil of an early human skeleton. To determine the age of the fossil, the archaeologist utilizes a technique called carbon dating, where the relative amount of carbon-14 can help determine the age of the fossil. Carbon-14 has a half-life of about 5700 years. He finds that the fossil contains 15% of the amount of carbon-14 anticipated when compared to a living femur of the same size. The decay of carbon-14 can be calculated as shown below, where N0 is original amount of carbon-14, t is the time of decay, in years, r represents the rate of decay, and N(t) represents the amount of carbon-14 remaining. Rounded to the nearest year, the skeleton is approximately years old.