The weekly salaries of 100 recent graduates of a private women's college are normally distributed with a mean of $600 and a standard deviation of $80. Determine the interval about the sample mean that has a 1% level of confidence. Use t=2.58

I don't know.

600/sqrt100
60
80+-2.58*60
2334.8 and -74.8

Its 600 +_ 2.58*80