To describe and correct the error, let's first analyze the the exponential decay model. In the model, is the initial amount and is the percent decrease or decay rate written as a decimal. The quantity is the decay factor or base. In the given information, is the decay rate which must be written as a decimal. The error is about finding the decay factor. Ron-Jon added the decay factor to Instead, the decay rate must be subtracted from Therefore, the model can be corrected as shown below.