Question

A plastic box $1.5m$ long, $1.25m$ wide and $65cm$ deep is to be made. It is opened at the top. Ignoring the thickness of the plastic sheet, determine:

The area of the sheet required for making the box.

• A. $5.45$ $m^2$
• B. $6.45$ $m^2$
• C. $5.15$ $m^2$
• D. $7.45$ $m^2$

Answer 1

The correct option is A $5.45$ $m^2$

The box is in the shape of a cuboid.
To find the area of the sheet required, we need to calculate the surface area of the cuboidal box and subtract the area of the top cover as it is an open box.

Total surface area of a cuboid of length $l$, breadth $b$ and height $h$

$=2(l\times b+b\times h+l\times h)$
So, the total surface area of the box with length $=1.5m$, breadth $=1.25m$ and height $=65cmor0.65m$

$=2(1.5\times 1.25+1.25\times 0.65+0.65\times 1.5)=2(1.875+0.8125+0.975)=7.325m^2$

Area of the top cover $=1.5\times 1.25=1.875m^2$

Hence, area of the metal sheet required to make the open tank $=7.325-1.875=5.45m^2$