Q.A research desires to identify the mean age of full-time students in a university. A random sample of 400 surveyed students indicates a mean age of 26.2 years, with a standard deviation of 5.6 years. If you were asked to interpret this data at a confidence level of 95%, what would your confidence interval be? Assume a normal distribution for the variable being investigated.

A. I know 95% = 1.96

I dont really know which formula im supposed to use its notz= (X- μ) / σ is it?