If(n ≥ 30) Confidence Interval = x ± zα2×(σn√) If(n < 30) Confidence Interval = x ± tα2×(σn√)

but in our case n=60 which means is greater than 30. Therefore, we use the z-Test tables Where, x = 19 σ = 1 α = 1 - (95/100) Zα2 = Value of the z-table tα2 = Value of the t-table.