A biologist was interested in determining whether sunflower seedlings treated with an extract from Vinca minor roots resulted in a lower average height of sunflower seedlings than the standard height of 15.7 cm ( = 3.5 cm). The biologist treated a random sample of n = 31 seedlings with the extract and subsequently obtained the sample mean: 13.8 cm. Use a 0.01 level of significance to test the hypothesis that = 15.7 (Ho) against the alternative that < 15.7 (H1).