If the distribution of intra-ocular pressure (IOP) seen in 100 glaucoma patients has an average 30 mm with a SD of 1.0, what is the lower limit of the average IOP that can be expected 95% of times?

In the given question, Mean (μ) = 30 mm and SD (σ) = 1.0 mm Thus, 95% values are contained in the range of Mean ± 2 SD (µ ± 2σ) or 30 ± 2 (1) So, 95% values are contained in the range 30 – 2 mm and 30 + 2 mm OR between 28 and 30 mm.