90. Stopping distances, again. For another test of the tires in Exercise 89, the company tried them on 10 different cars, recording the stopping distance for each car on both wet and dry pavement. Results are shown in the following table.

a) Find a 95% confidence interval for the mean dry pavement stopping distance. Be sure to check the appropriate assumptions and conditions, and explain what your interval means.

b) Find a 95% confidence interval for the mean increase in stopping distance on wet pavement. Be sure to check the appropriate assumptions and conditions, and explain what your interval means.

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Stopping Distance (ft) Car # |Dry Pavement | Wet Pavement 10 1234567 7800 150 201 2 147 220 136 192 134 146 130 182 134 173 134 202 128 180 9 136 192 158 206