If the distribution of intraocular pressure (IOP) seen in 100 glaucoma patients has an average 30 mm with an SD of 1, what is the lower limit of the average that can be expected 95% of times -
(A) 28 (B) 26 (C) 32 (D) 25
(A) 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 ± 2s) 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.