An investigator wants to study an enzyme that is known to obey Michaelis-Menten kinetics. The investigator runs an assay and observes that the initial velocity (v) is 0.8-times Vmax. Given this information, what is the value of the substrate concentration? Express your answer as the decimal (to the nearest tenth) by which one would multiply Km. For example, if you determined that the substrate concentration was two-and-one-half times Km, you would enter 2.5 for your answer.