Here is a table: $ \begin{array}{ c c c c c c c } Trial number & Time for 20 cycles & Period & Frequency & Wavelength & Velocity (wavelength*frequency) & Velocity (wavelength/period) \\ 1 & 19.08 & 0.9540 & 1.048 & 8.000 & 8.384 & 8.386 \\ 2 & 10.10 & 0.5050 & 1.980 & 4 & 7.920 & 7.921 \\ 3 & 7.65 & 0.383 & 2.61 & 2.67 & 6.97 & 6.97 \\ 4 & 5.08 & 0.254 & 3.94 & 2.00 & 7.88 & 7.87 \end{array} $
I used four significant digits for all the measurements for trial one and two, three significant digits for trails three and four. I thought I was gonna get the same velocity by both methods. But only the velocity results for trail three conform. Why?
