Answer: The effect of manganese (Mn) on wheat growth is

Chapter 13, Problem 13.75

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The effect of manganese (Mn) on wheat growth is examined in the article Manganese Deficiency and Toxicity Effects on Growth, Development and Nutrient Composition in Wheat (Agronomy J., 1984: 213217). A quadratic regression model was used to relate y plant height (cm) to x log10(added Mn), with M as the units for added Mn. The accompanying data was read from a scatter diagram appearing in the article. x | 1.0 .4 0 .2 1.0 y | 32 37 44 45 46 x | 2.0 2.8 3.2 3.4 4.0 y | 42 42 40 37 30 In addition, 0 41.7422, 1 6.581, 2 2.3621, s 0 .8522, s 1 1.002, s 2 .3073, and SSE 26.98. a. Is the quadratic model useful for describing the relationship between x and y? [Hint: Quadratic regression is a special case of multiple regression with k 2, x1 x, and x2 x2 .] Apply an appropriate procedure. b. Should the quadratic predictor be eliminated? c. Estimate expected height for wheat treated with 10 M of Mn using a 90% CI. [Hint: The estimated standard deviation of 0 1 2 is 1.031.]