question_answer 12)

The mass of a box measured by a grocer's balance is 2.3 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 and (b) the difference in the masses of the pieces to correct significant figures? 

Answer:

(a) Total mass of the box = 2.3 kg + 0.02015 kg + 0.02017 kg = 2.34032 kg = 2.3 kg. The result has been rounded off to first place of decimal because mass (2.3 kg) of box has digits upto this place of decimal. (b) Difference in masses of 2 gold pieces = 20.17 g-20.15 g= 0.02 g.