Question

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 (i) the total mass of the box? (ii) the difference in the masses of the pieces to correct significant figures?

Answer 1

(i) Total mass of the box

= (2.3 + 0.02017 + 0.02015) kg

= 2.34032 kg

Since, the last number of significant figure is 2, 

therefore, the total mass of the box = 2.3 kg

(ii) Difference of mass = (20.17 – 20.15) = 0.02g 

Since, there are two significant figures so the difference in masses to the correct significant figures is 0.02 g.

(i) The total mass of the box to correct significant figures is 2.3 kg.

(ii) The difference in the masses to correct significant figures is 0.02 g.