30) What is the most common method to renew vehicles registration? In checking a random sample of 500 motor vehicle renewal registrations in one county, the finance department found that 200 were mailed, 160 were paid in person at the county finance department office, and the remainder was paid online at the county's Web site. Phone registration renewals were not available. a. Estimate the population proportion to pay for vehicle registration renewals in person at the county finance department office. Use a 90% confidence level. b. Estimate the population proportion of online renewals. Use a 95% confidence level.