Conduct appropriate hypothesis test using significance level/Statistics
An automobile manufacturer gives a 5 years/60,000 mile warranty on its drive train. Historically, 7% of this manufacturer’s cars have required service under this warranty. Recently, a design team proposed an improvement that should extend the drive train’s life. A random sample of 200 cars underwent 60,000 miles of road testing, in which tests the driver train of 12 cars failed.
a. Conduct the most appropriate hypothesis test using a 0.05 significance level.
b. Construct a 95% confidence interval for the true proportion of automobiles with drive trains that fail.
