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: 213–217). 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.