Question

(1) A book with measures 25 cm 18 cm 4 cm is to be covered with a brown paper. Hur
many metres of brown paper of width 40 cm are required to cover 100 such books?
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Answer 1

Given :

A book with measures 25 cm × 18 cm × 4 cm

Find the Total surface area of book :-

Total surface area = 2 (lb + bh + lh) square units

= 2 (25 × 18 + 18 × 4 + 25 × 4) cm²

= 2 (450 + 72 + 100) cm²

= 2 (622) cm²

= 1244 cm²

Total surface area of 100 books

= 100 × 1244 cm² = 124400 cm²

Surface area 1 m brown paper = 100 cm × 40 cm = 4000 cm²

Therefore,

Hence,

31.1 metres of brown paper wil cover the total surface of 100 such books.