Question

The mass of a box measured by a grocer’s balance is 2.30 kg. Two gold pieces of masses 20.15 $\text g$ and 20.17 $\text g$ are added to the box. What is

1. the total mass of the box,
2. the difference in the masses of the pieces to correct significant figures ?

Answer 1

a. Mass of grocer’s box = 2.300 $\text {kg}$
Mass of gold piece I = 20.15 $\text g$ = 0.02015 $\text {kg}$
Mass of gold piece II = 20.17 $\text g$ = 0.02017 $\text {kg}$
Total mass of the box = 2.3 + 0.02015 + 0.02017 = 2.34032 $\text {kg}$
In addition, the final result should retain as many decimal places as there are in the number with the least decimal places.

Hence, the total mass of the box is 2.3 $\text {kg}$.

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b. Difference in masses = 20.17 - 20.15 = 0.02 $\text g$
In subtraction, the final result should retain as many decimal places as there are in the number with the least decimal places.