1-Find the critical value, z/2, that corresponds to an 88% confidence interval. You may want to draw a picture to show your work.

2-. A manufacturer makes a particular car part that is supposed to have a mean weight of 30 g. An angry customer suspects (claims) that the mean weight is actually less than 30 g. The mean weight of a random sample of 25 of these car parts is 29.2 g with a standard deviation of 4.2 g. The sample is normally distributed. At the 0.05 significance level, test the customer's claim that the sample is from a population where the mean weight is less than 30 g. a) State the claim, null hypothesis and alternative hypothesis. Claim: Ho and H1 b) Find the t-statistic. c) Find the p-value. f) Do you reject the null or fail to reject the null? Explain your answer either using your p-value or t-statistic and critical value. d) Interpret the results of your hypothesis test. Specifically, is there evidence to support the angry customers claim that the mean of the population is less than 30? Explain.