Question.
The paint in a certain container is sufficient to paint an area equal to 9.375 m2. How many bricks of dimensions 22.5 cm × 10 cm × 7.5 cm can be painted out of this container?
Solution:
Total surface area of one brick = 2(lb + bh + lh)
$=[2(22.5 \times 10+10 \times 7.5+22.5 \times 7.5)] \mathrm{cm}^{2}$
$=2(225+75+168.75) \mathrm{cm}^{2}$
$=(2 \times 468.75) \mathrm{cm}^{2}$
$=9375 \mathrm{~cm}^{2}$
Let n bricks can be painted out by the paint of the container.
Area of $n$ bricks $=(n \times 937.5) \mathrm{cm}^{2}=937.5 \mathrm{n} \mathrm{cm}^{2}$
Area of $n$ bricks $=(n \times 937.5) \mathrm{cm}^{2}=937.5 n \mathrm{~cm}^{2}$
Area that can be painted by the paint of the container $=9.375 \mathrm{~m}^{2}=93750 \mathrm{~cm}^{2}$
$\therefore 93750=937.5 n$
$n=100$
Therefore, 100 bricks can be painted out by the paint of the container.
Total surface area of one brick = 2(lb + bh + lh)
$=[2(22.5 \times 10+10 \times 7.5+22.5 \times 7.5)] \mathrm{cm}^{2}$
$=2(225+75+168.75) \mathrm{cm}^{2}$
$=(2 \times 468.75) \mathrm{cm}^{2}$
$=9375 \mathrm{~cm}^{2}$
Let n bricks can be painted out by the paint of the container.
Area of $n$ bricks $=(n \times 937.5) \mathrm{cm}^{2}=937.5 \mathrm{n} \mathrm{cm}^{2}$
Area of $n$ bricks $=(n \times 937.5) \mathrm{cm}^{2}=937.5 n \mathrm{~cm}^{2}$
Area that can be painted by the paint of the container $=9.375 \mathrm{~m}^{2}=93750 \mathrm{~cm}^{2}$
$\therefore 93750=937.5 n$
$n=100$
Therefore, 100 bricks can be painted out by the paint of the container.