Given 4 measured values below, is the person above the blood alcohol limit within a 95% confidence limit?

Question

The legal limit for blood alcohol is 0.080. The measured values are 0.080, 0.085, 0.085, 0.079. The mean is 0.0823

Is the person above the blood alcohol limit within a 95% confidence limit in the following two situations:

A) well characterized σ = 0.003

B)unknown standard deviation s=?