I need your help answering these questions. Please help me by answering and showing explanations.

Problem 1. The confidence interval for the population mean of the failure strength of a column is given by (233, 237) psi. (a) What was the sample mean of the failure strength? (b) Three confidence intervals were calculated from the same sample data, with confidence levels 90%, 95%, and 97.5%. The intervals are (233, 237), (231, 239), and (234, 236). Which interval corresponds with each confidence level? Give a reason for your answer. Problem 2. Assume that the failure strength of a column can be represented by a normal distribution where the population standard deviation is 4 psi. If you need the width of the 95% confidence interval to be 3 psi, how large of a sample do you need