In a study of the correlation between the amount of rainfall and the quantity of air pollution removed, the following data were collected:
x, daily rainfall y, particulate removed
(0.01 centimeter) (micrograms per cubic meter)
4.3 126
4.5 121
5.9 116
5.6 118
6.1 114
5.2 118
3.8 132
2.1 141
7.5 108
a) Sketch a scatter diagram for the samples
b) Calculate the sample correlation coefficient r and interpret the relation between the amount of rainfall and the quality of air pollution removed.