A study in 2000 by the National Highway Traffic Safety Administration estimated that failure to wear seat belts led to 9200 deaths in the previous year, and that the number of deaths would decrease by 270 for every 1 percentage point gain in seat belt usage. Let ŷ = predicted number of deaths in a year and x = percentage of people who wear seat belts.
a. Report the slope b for the equation ŷ = a + bx.
b. If the y -intercept equals 28,910, then predict the number of deaths in a year if (i) no one wears seat belts, (ii) 73% of people wear seat belts (the value in 2000), (iii) 100% of people wear seat belts.