From a random sample of 250 owners of medium sized vehicles, it is found that the owners average monthly car insurance premium for a full comprehensive cover is R550.

1. Construct a 95% Confidence interval for the average monthly premiums for owners of medium sized vehicles and interpret the result (10)

2. If the sample size is to increase to 500 car owners and the population standard deviation becomes R58, estimate the 90% confidence interval of the total monthly premium of the company and interpret your results (10)