Suppose a hybrid automobile has an average fuel economy of 40 mi/gal, and a comparable nonhybrid averages 25 mi/gal. If the hybrid model costs $6000 more than the nonhybrid, and gasoline averages $2.50 per gallon, which model would be less expensive over a lifespan of 125,000 miles? (See example 18 on page 307.)

Anew test for ra is being developed. the test is administered to 750 patients with ra and 750 without ra. for the sake of the question, assume the prevalence of ra in this population is 50%. of the 750 patients with ra, 575 have a positive result. of the 750 patients without ra, 150 have a positive result. what is the positive predictive value of the new test? a575/(575+150) b. 600/(600+ 150) c. 575/(575+125) d. 600/(600+ 125)