Insurance companies are interested in knowing the population percent of drivers who always buckle up before riding in a car. They randomly survey 400 drivers and find that 311 claim to always buckle...

Insurance companies are interested in knowing the population percent of drivers who always buckle up before riding in a car. They randomly survey 400 drivers and find that 311 claim to always buckle up. Construct a 80% confidence interval for the population proportion that claim to always buckle up.