Mary wants to decorate her Christmas tree. She wants to place the tree on a wooden block covered with coloured paper with picture of Santa Claus on it. She must know the exact quantity of paper to buy for this purpose. If the box has length, breadth and height as $80\ cm, 40\ cm$ and $20\ cm$ respectively. How many square sheets of paper of side $40\ cm$ would she require?

Given:

The box has length, breadth and height as $80\ cm, 40\ cm$ and $20\ cm$ respectively. 

To do:

We have to find the number of square sheets of paper of side $40\ cm$ that she would require.

Solution:

Length of the box $(l) = 80\ cm$

Breadth of the box $(b) = 40\ cm$

Height of the box $(h) = 20\ cm$

Therefore,

Total surface area of the box $= 2(lb + bh + hl)$

$= 2(80 \times 40 + 40 \times 20 + 20 \times 80)$

$= 2(3200 + 800 + 1600)$

$= 2 \times 5600$

$= 11200\ cm^2$

Size of each paper sheet $= 40\ cm$

This implies,

Area of one sheet $= (40\ cm)^2$

$= 1600\ cm^2$

Therefore,

The number of sheets required for the box $= \frac{11200}{1600}$

$= 7$ sheets.

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Updated on: 10-Oct-2022

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