The service time of the first service of a population of Mercedes Benz cars, denoted by X, is assumed to be normally distributed. A random sample of 250 Mercedes Benz cars yields the following results about the first service time: x = 70 minutes and s = 81 minutes 1.1 Determine a 95% confidence interval for the variance of X. Interpret it. (10) 1.2 Three years ago, a study was conducted on the divergences of Mercedes Benz first service times. It was found that the standard deviation of the service time of this population was 7 minutes. Can it be concluded that nowadays the variation of Mercedes Benz service has increased or decreased? (5)