Hi Normal distribution: μ = 30min and σ =6 n = 10 mean = 20min Ho: μ = 30 Ha: μ < 30 a=0.10, one-tailed:df9 t = 1.38 critical value t-value = -10(√10) /6 = -5.27 |-5.27| > 1.38 Reject Ho, evidence indicates mean is < 30min Wish You the Best in your Studies.