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NCERT Solutions Ganita Prakash (Part 2) Chapter 7 Areas in Real Life — In-text Questions

Book page 170 Updated on2026-09-05

Q1.
What do you think is the area of an A4 sheet? Its sidelengths are 21 cm and 29.7 cm. Now find its area.
Answer
Area = 21 × 29.7
= 21 × 29 + 21 × 0.7
= 609 + 14.7
= 623.7 cm²
Did you know? That is a little over 600 cm², or about 0.06 m². Fold an A4 sheet in half and you get A5, of area about 311.85 cm² — every step down the A series halves the area.
Q2.
What do you think is the area of the tabletop that you use at school or at home? You could perhaps try to visualise how many A4 sheets can fit on your table.
Answer

Measure your own table, but here is a typical calculation for a school desk of 120 cm by 60 cm.

Area of the tabletop = 120 × 60 = 7200 cm²

Number of A4 sheets ≈ 7200 ÷ 623.7 ≈ 11 or 12 sheets

Lay the sheets out to check: two columns of A4 across the 60 cm width (21 × 2 = 42 cm, with 18 cm spare) and four rows along the 120 cm length (29.7 × 4 = 118.8 cm). That is 8 sheets without overlapping, plus a strip left over — sheets have to fit whole, so the practical count is a little less than the arithmetic one.

Why it happens: dividing areas tells you how much surface there is, but not whether the pieces can be packed without cutting. Area is an upper limit for such packing questions, never a guarantee.
Q3.
Express the following lengths in centimeters: (i) 5 in (ii) 7.4 in
Answer

Multiply by 2.54, since 1 in = 2.54 cm.

(i) 5 in = 5 × 2.54 = 12.7 cm

(ii) 7.4 in = 7.4 × 2.54 = 18.796 cm
Q4.
Express the following lengths in inches: (i) 5.08 cm (ii) 11.43 cm
Answer

Divide by 2.54, since 2.54 cm = 1 in.

(i) 5.08 ÷ 2.54 = 2 in

(ii) 11.43 ÷ 2.54 = 4.5 in
Check it yourself: 2 × 2.54 = 5.08 ✓ and 4.5 × 2.54 = 11.43 ✓
Q5.
How many cm² is 1 in²?
Answer

A square of side 1 in is the same square as one of side 2.54 cm.

1 in² = (2.54 cm) × (2.54 cm)
= 2.54² cm²
= 6.4516 cm²
Why it happens: the conversion factor for area is the square of the conversion factor for length. Both sides of the square are stretched by 2.54, so the area is stretched by 2.54 × 2.54. This is the scaling rule from page 152 in a new dress.
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