with work shown please

Suppose that for a given signal, you have a signal-to-noise ratio of 4 . In order to perform the measurement with the desired quality, you want to have a S/N of 20. How many more measurements must be done to achieve this outcome? (You may either solve for "how many times more" measurements, or decide on how many measurements were done originally and calculate how many more are needed. Clearly label your answer so that I know which approach was used. Also, recall that measurements are a wholenumber quantity.)