Dis gegee dat X normaal verdeel is met gemiddelde μ = 0 en variansie σ² = 15. ’n Ewekansige steekproef van grootte n = 64 word uit hierdie populasie gekies. Dus is P(-1.5 ≤ x̄ ≤ 0.5)  gelyk aan / It is given that X is normally distributed with mean μ = 0  and variance σ² = 15. A random sample of size n = 64 is selected from this population. Therefore P(-1.5 ≤ x̄ ≤ 0.5) is equal to