vadim weighs himself on his bathroom scale. the smallest divisions on the scale are 1-pound marks, so the least count of the instrument is 1 pound. vadim reads his weight as closest to the 142-pound mark. he knows his weight must be larger than 141.5 pounds (or else it would be closer to the 141-pound mark), but smaller than 142.5 pounds (or else it would be closer to the 143-pound mark). so vadim's weight must be