For a random sample of 256 owners of medium-sized cars, it was found that their average monthly car insurance premium for comprehensive cover was R356. Assume that the population standard deviation is R44 per month and that insurance premiums are normally distributed. (a) Find the 95% confidence interval for the average monthly comprehensive car insurance premium paid by all owners of medium-sized cars. Interpret the result. (Use the z-table value=1.645) (b) What is the difference point estimate and estimator. write properties of good estimators. (c)What is the purpose of a confidence interval?