A researcher want to determine an interval estimate for the average weight of adult gorillas in pounds. She wants to be 99% certain that she is within 4.8 pounds of the true average. From past studies, it is known that the standard deviation of the weights of adult gorillas is 13 pounds.

1. What is the critical value that corresponds to the given level of confidence? Round your answer to two decimal places.
2. What is the minimum sample size necessary to estimate the population mean? Round your answer up to the next integer.