The z-value is 2.3 for the event of 60.5 (x = 60.5) occurrences with the mean of 50 (μ = 50) and standard deviation of 5 (σ = 5). The computation takes the form of (x – μ) / σ = (60.5 – 50) / 5 = 11.5 / 5 = 2.3).
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