Researchers wanted to determine whether seeding (treating) isolated cumulus clouds in south Florida with silver iodide smoke increases rainfall. They randomly assigned 26 clouds to be seeded and 26 clouds to not be seeded. The amounts (in acre-feet) of rainfall from the clouds in the two groups are shown in Table 18.

a. Construct two dot plots that share the same horizontal axis to describe the rainfall from the two groups of clouds.
b. On the basis of the shapes of the two distributions, would it be better to use the means or the medians to measure the centers? Explain.
c. On the basis of your response to part (b), measure the centers of the two distributions.
d. Did one of the seeded clouds tend to have greater, equal, or less rainfall than one of the control clouds?
e. In general, we cannot be certain that seeding clouds in south Florida increases rainfall. Is that because of possible sampling bias, sampling error, both, or neither? Explain.

Table 18 Rainfall from Seeded and Control Clouds Rainfall acre-feet) Seeded Clouds Control Clouds 16978 119.0 302.8 345.5 411 4.1 95.0 321.2 4.9 31.4 92.4 147.8 21.7 334.1 274.7 115.3 244.3 36.6 7.7 1656.0 430.0115 830.1 6.3 129.6 175 40.6 32.7 978.0 163.0 24.4 1202.6 4.9 81.2 28.6 17.3 29.0 68.5 489.1 703.4 2745.6 200.7 87.0 274.7 198.6 255.0 242.5 118.3 3724 1.0 47.3 26.1