Stachybotrys chartarum (atra) is the black mold that has most been associated with media reports on the toxic effects of fungal exposure. It prefers gypsum wall board as a substrate and requires very high relative humidity levels to grow. Stachybotrys chartarum is known to produce the mycotoxin, satratoxin.
When total utility is rising with the increased consumption of a good, but is rising at a decreasing rate, marginal utility is negative. b. When total utility is rising with the increased consumption of a good, and is rising at an increasing rate, marginal utility is positive. c. At the maximum point of a hill-shaped total utility curve, marginal utility is infinite. d. When total utility is falling with the increased consumption of a good, but is falling at a decreasing rate, marginal utility is positive.
In an economy with money, the marginal utility of a quantity is simply that of the best good or service that it could purchase. In this way it is useful for explaining supply and demand, as well as essential aspects of models of imperfect competition.