Twelve cars were equipped with radial tires and driven over a test course. Then the same 12 cars (with the same drivers) were equipped with regular belted tires and driven over the same course. After each run, the cars' gas economy (in kilometer/liter) was measured. Data are shown below. Assume gas economy for both types of tires are normally distributed. Do the data provide enough evidence to show that radical tires produce higher gas economy? What's the difference between population means for gas economy? Gas eco (radial) 4.2
Twelve cars were equipped with radial tires and driven over a test course. Then the same 12 cars (with the same drivers) were equipped with regular belted tires and driven over the same course. After each run, the cars' gas economy (in kilometer/liter) was measured. Data are shown below. Assume gas economy for both types of tires are
Gas eco (radial) 4.2 4.7 6.6 7.0 6.7 4.5 5.7 6.0 7.4 4.9 6.1 5.2
Gas eco (belted) 4.1 4.9 6.2 6.9 6.8 4.4 5.7 5.8 6.9 4.7 6.0 4.9
What is the 90% confidence interval? Round to 4 decimal places if necessary.
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