Question

the mass of a box measured by a grocer balance Is 2.3 kg . two 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 1

Here, mass of the box, m=2.3kg
Mass of one gold piece, m
1
​
=20.15g=0.02015kg
Mass of other gold piece, m
2
​
=20.17g=0.02017kg
∴ Total mass = m+m
1
​
+m
2
​
=2.3kg+0.02015kg+0.02017kg=2.34032kg
As the result is correct only upto one place of decimal, therefore, on rounding off, we get Total mass =2.3kg

Answer 2

Hey friend

# Answer-

a) Total mass of the box = 2.3 kg

b) Difference in masses = 0.02 g

# Given-

Mass of grocer’s box = 2.300 kg = 2.3 kg ...(2 significant figures)

Mass of 1st gold piece = 20.15 g = 0.02015 kg ...(4 significant figures)

Mass of 2nd gold piece = 20.17 g = 0.02017 kg ...(4 significant figures)

# Solutions-

After addition as well as substraction, mass should retain least significant figures i.e. here 2 and 4 respectively.

a) Total mass of the box

= 2.3 + 0.02015 + 0.02017

= 2.34032 kg

= 2.3 kg ...(2 significant figures)

b) Difference in masses

= 20.17 – 20.15

= 0.02 g ...(only 2 significant figures available)

Hope that helped you...