What will be the difference in mass (in g) between two packets each containing 500 sheets of 80 GSM and 70 GSM papers of size 20 cm x 30 cm? (GSM = g/m²)

Correct option is C

Given:

Two packets:

One has 500 sheets of 80 GSM paper

One has 500 sheets of 70 GSM paper

Size of each sheet = 20 cm × 30 cm

GSM = grams per square meter (g/m²)

Find the difference in mass (in grams) between the two packets.

Formula:
Mass of one sheet = (Area in m²) × GSM
Total mass = (Mass of one sheet) × (Number of sheets)
Difference = Mass of 80 GSM packet – Mass of 70 GSM packet

Solution:
​
Step 1:
Find the area of one sheet:
Area = 20 cm × 30 cm
Convert into meters:
Area = (20/100) × (30/100) = 0.2 × 0.3 = 0.06 m²

Step 2:
Mass of one sheet of 80 GSM paper = 80 × 0.06 = 4.8 g
Mass of one sheet of 70 GSM paper = 70 × 0.06 = 4.2 g

Step 3:
Mass of 500 sheets:

For 80 GSM: 500 × 4.8 = 2400 g

For 70 GSM: 500 × 4.2 = 2100 g

Step 4:
Difference = 2400 – 2100 = 300 g

Final Answer: (c) 300