a. Is repeated sampling an example of independent or dependent sampling? Explain your answer. 2 marks b. An economist is interested in the difference in the average wage of university graduates living in London and those living in Manchester. They take a random sample of 21 university graduates living in London and 21 university graduates living in Manchester. They ask each participant how much they earn in a year. The variance of income in London is known to be higher than in Manchester. The results obtained are shown below: Annual Income London Manchester N 21 21 Mean 35957 29778 Variance 12,974,987 8,834,132 Covariance 84161 Are the samples independent or dependent? Construct a 95 percent confidence interval for the difference in the two population means 9 marks