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, (b) the difference in the masses of the pieces to correct significant figures?
mi=2.300kg ( 2 significant digits) m1=20.15g=0.02015kg ( 4 significant digits) m2=20.175g=0.02017kg ( 4 significant digits) (a) Adding M=Σm=2.3+0.02015+0.02017kg=2.34032kg But since the initial mass has least 2 signifincant digits, the final mass should not have more than 2 significant digits Hence, M=2.3Kg (b) Subtracting m2−m1=0.02g Since the initial mass has 4 significant digits, the result can have 4 or less significant digits Hence here the no. of significant digit =2
