The mass of a box measured by a grocer's balance is 2.3 kg. Two gold pieces of masses 20.15 g and 20.17g are added to the box. What is (a) total mass of the box (b) the difference in masses of gold pieces to correct significant figures.

Explanation

Mass of box = 2.3 kg
Mass of gold pieces = `20.15 + 20.17 = 40.32 g = 0.04032 kg`.
Total mass = `2.3 + 0.04032 = 2.34032 kg`
In correct significant figure mass = 2.3 kg (as least decimal)