Given : σ = 5, n = 25, s = 8, α = 0.05
H0 : σ = 5
H1 : σ ≠ 5(Two tailed test)
Under H0, the test statistic is : –

At α = 0.05 for (n – 1) = 25 = 1
= 24 d.f the two tail critical values
are k1 = 13.85 and k2
Here χ2cal = 64 lies in Rejection region (RR)
∴ H0 is rejected and H1 is accepted
conclusion : σ ≠ 5.