To test the effectiveness of a carbon monoxide (CO) alarm, a company begins a controlled experiment that dellivers carbon monoxide to a closed room at the rate of 1.5% of the current amount in the room every 2 hours. Find an exponential model for the amount of CO in the room C (in ppm) as a function of time t (in hr) from the beginning of the experiment when there are 50 parts per million co in the room. C=