6} We make four independent measurement of the conductivity of a certain material. We assume that the measurement errors are normal and have zero expectation. We also assume that all measurements have the same standard deviation. The measurement values are so = 1a}:2 = 14;; = no = s. a} Estimate the conductivity and give a 95% condence interval assuming that the standard deviation for one measurement is or = 4L. h} Estimate the standard deviation. c} Test the hypothesis that the conductivity is 7 assuming the standard deviation to be equal to 3. What is the p-value'.' d} Do you reject the hypothesis in problem c on the 10% signicance level