Umi's test grades for this semester are in the list shown. The mean of her test grades is 82.4. 86,93,90,85,42,91,90

A33 gram sample of a substance that's used to detect explosives has a k-value of 0.1473. n = noekt no = initial mass (at time t = 0) n = mass at time t k = a positive constant that depends on the substance itself and on the units used to measure time t = time, in days