=+They took a sample of 4 springs each hour and recorded the results in the following table.

Sample 1 Sample 2 Sample 3 Sample 4 Hour 1 501.02 497.24 501.44 504.20 Hour 2 501.65 501.04 500.46 500.92 Hour 3 504.34 498.74 502.07 500.02 Hour 4 501.10 503.51 500.50 501.71 Hour 5 499.80 501.22 498.26 498.61 Hour 6 498.89 504.53 495.54 499.63 Hour 7 499.47 499.06 495.21 498.68 Hour 8 497.90 505.37 501.27 501.84 Hour 9 497.12 499.15 497.57 499.05 Hour 10 498.35 501.11 497.00 501.82 Hour 11 500.34 497.96 500.32 500.67 Hour 12 499.33 502.39 501.22 497.36 Hour 13 500.68 498.90 500.95 497.85 Hour 14 501.39 505.99 502.07 494.08 Hour 15 499.74 500.05 500.60 501.79 Hour 16 500.41 499.33 500.44 501.95 Hour 17 495.87 497.38 499.70 501.08 Hour 18 500.92 497.80 500.56 503.12 Hour 19 498.00 497.57 501.18 503.06 Hour 20 499.44 500.72 502.36 503.56 Hour 21 497.89 499.70 501.57 500.75 Hour 22 499.22 500.99 502.09 501.18 Hour 23 502.10 501.35 501.18 501.09 Hour 24 500.03 496.48 504.98 502.88