6. Weekly wages are known to be normally distributed with a standard deviation of 5.10. An economist claims that the mean weekly income in this industry is 70.40. A random sample of 35 workers yields a mean income of 75.20. a) What null and alternative hypothesis would you specify? b) Generate a 95% confidence interval for the sample mean. c) Use a classical hypothesis test at the 5% level of significance to test the null hypothesis.