Kylie is preparing for the science fair which will take place in six weeks. She has three plants that she has grown from seeds, which she considers to have height 0 centimeters, and she is measuring their heights as she applies different treatments to each. The third plant is planted in the same soil as the others, but it receives only light and water. After 2 weeks, it is 6 centimeters tall. If it continues growing at this rate, how tall will it be after 6 weeks?