Trace metals found in wells affect the taste of drinking water, and high concentrations can pose a health risk. Researchers measured the concentration of zinc (in milligrams/liter) near the top and the bottom of 10 randomly selected wells in a large region. The data are provided in the following table.

a. Make a dotplot of the difference (Bottom – Top) in the zinc concentrations for these 10 wells.

b. Describe what the graph reveals about whether the amount of zinc at the top and bottom of the wells is the same, on average.

c. Calculate the mean difference and the standard deviation of the differences. Interpret the mean difference.

Transcribed Image Text:

Well 1 2 3 5 6 7 8 10 Bottom 0.430 0.266 0.567 0.531 0.707 0.716 0.651 0.589 0.469 0.723 Тоp 0.415 0.238 0.390 0.410 0.605 0.609 0.632 0.523 0.411 0.612 Difference 0.015 0.028 0.177 0.121 0.102 0.107 0.019 0.066 0.058 0.111