Need help solving and understand calculator functions, I use a TI-84plus

A financial advisor wants to construct a 95% confidence interval to estimate the mean retirement age for workers in the United States. The financial advisor takes a random sample of 27 recently retired workers and asks each participant for his/her age at retirement. The sample mean age is 60.7 years and the standard deviation is 5.9 years. The table below shows select t multipliers.