Ho: \\( \\mu=2.45 \\) left tail \\[ \\begin{array}{l} t=\\frac{\\bar{x}-\\mu}{s / \\sqrt{n}}=\\frac{1.45-1.21}{0.4 / \\sqrt{28}}=3.1750 \\\\ t_{0 \\times / 2}=t_{0.005 / 2}=t_{0.0025}=2.771 \\\\ d t=28-1=27 \\text { rejectnu } \\\\ p \\text {-value }=0.0018 \\text {, reject null } \\\\ \\end{array} \\] Their exhaust does put out onore pollution