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 ?

Explanation

Here, mass of the box, m = 2.3 kg
Mass of one gold piece,
`m_(1)=20.15 g = 0.02015 g`
Mass of another gold piece,
`m_(2)=20.17g=0.02017kg`
(a) Total mass = `m+m_(1)+m_(2)`
`" "=2.3+0.02015+0.02017`
`" "=2.34032 kg`
`" "` As the result is correct only upto one place of decimal, therefore, on rounding off total mass = 2.3 kg
b) Difference in masses
`" "=m_(2)-m_(1)=20.17-20.15`
`=0.02g` (correct upto two places of decimal)