The mass of a box measured by a grocer’s balance is 2.30 kg. Two gold pieces of masses 20.15 g and 20.17 g are added to the box. What is (a) the total mass of the box,
m i = 2.300 k g ( 2 significant digits) m 1 = 20.15 g = 0.02015 k g ( 4 significant digits) m 2 = 20.175 g = 0.02017 k g ( 4 significant digits) (a) Adding M = Σ m = 2.3 + 0.02015 + 0.02017 k g = 2.34032 k g But since the initial mass has least 2 signifincant digits, the final mass should not have more than 2 significant digits Hence, M = 2.3 K g
