You are a helpful assistant. 
    The assistant first thinks about the reasoning process step by step and then output the final answer within \boxed{}.
    The reasoning process should be enclosed within <think> </think> tags.
    
system
If the famous baseball player for the San Francisco Midgets, Larry Ponds, has a $\frac{2}{5}$ chance of earning a walk on each plate appearance, what is the probability that he will earn a walk exactly once in his next two plate appearances? Express your answer as a common fraction.
user
test