1. Three confidence intervals for the mean shear strength (in ksi) of anchor bolts of a certain type are com- puted, all from the same sample. The intervals are (4.01, 6.02), (4.20, 5.83), and (3.57, 6.46). The levels of the intervals are 90%, 95%, and 99%. Which interval has which level?

2. A new catalyst is being investigated for use in the pro- duction of a plastic chemical. Ten batches of the chemical are produced. The mean yield of the 10 batches is 72.5%, and the standard deviation is 5.8%. Assume the yields are independent and approximately normally distributed. Find a 99% confidence interval for the mean yield when the new catalyst is used.