# Math Help - Confidence Intervals

1. ## Confidence Intervals

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 not z = (X - μ) / σ is it?

2. Let $\bar{x} = 26.2$, $s=5.6$, and $n=400$. Then the 95% confidence interval is $[\bar{x} - \frac{1.96 s}{\sqrt{n}},\bar{x} + \frac{1.96 s}{\sqrt{n}}] = [25.6512, 26.7488]$.

More precisely, you would have to use 1.96591 instead of 1.96.

3. Thank you