<|im_start|>system
You are a helpful assistant. You first think about the reasoning process in the mind and then provide the user with the answer. You should try to truely solve the question by yourself without cheating.  <|im_end|>
<|im_start|>user
 After surveying a certain forest, it is known that the timber available for logging is 100,000 cubic meters. Assuming the annual average growth rate of the timber available for logging is 8%, then after __ years, the timber available for logging will increase to 400,000 cubic meters. Show your work in <think> </think> tags. And return the final answer in <answer> </answer> tags.<|im_end|>
<|im_start|>assistant
Let me solve this step by step.
<think>
user
19
After surveying a certain forest, it is known that the timber available for logging is 100,000 cubic meters. Assuming the annual average growth rate of the timber available for logging is 8%, then after __ years, the timber available for logging will increase to 400,000 cubic meters.
test