Question

Dmitri wants to cover the top and sides of the box shown with glass tiles that are 5mm square. How many tiles does he need? ( The length is 15cm, the width is 20cm and the height is 9cm).

Answer 1

The Surface Area = lw + 2lh + 2wh;
The Surface Area = 15*20 + 2*15*9 + 2*20*9;
The Surface Area = 300 + 270 + 360;
The Surface Area = 570 + 360;
The Surface Area = 930cm^2;
The surface of glass tile is 5 × 5 = 25 cm^2;
Then, 930 ÷ 25 = 37.2;
He need 38 tiles to cover the top and sides of the box shown.

Answer 2

372

Explanation:

We are given that the dimensions of the box are,

Length = 15 cm, Width = 20 cm and Height = 9 cm.

We know that the box represents a cuboid.

Since, surface area of a cuboid = L×W + 2×L×H + 2×W×H

Thus, the surface area of the box = 15×20 + 2×15×9 + 2×20×9

i.e. Surface area = 300 + 270 + 360

i.e. Surface area = 930.

Thus, the surface area of the box is 930 cm² i.e. 9300 mm².

Further, the sides of the tiles are 5 mm and the tile represents a square.

So, the surface area of the tile = 5 × 5 = 25 mm².

This gives us that,

Number of tiles required to cover the box =
`(9300)/(25)` = 372.

Hence, Dmitri requires 372 tiles to cover the box.