Question

A plastic box $1.5$ m long, $1.25$ m wide and $65$ cm deep is to be made. It is opened at the top. Ignoring the thickness of the plastic sheet, determine:
(i) The area of the sheet required for making the box.
(ii) The cost of sheet for it, if a sheet measuring $1m^2$ costs Rs.$20$.

Answer 1

Length of plastic box I = $1.5m$
breadth b $=1.25m$
height , h $=65cm=0.65m$

⇒Area to be white-washed = Area of cuboid − Area of base.

(i) Area of sheet requred $=2lb+2bh+2lh-lb$

$=(1.5\times 1.25)+(2\times 1.25\times 0.65)+2\left(1.5\right)\left(0.65\right)$
$=1.875+1.625+1.950$
$A=5.45c{m}^2$
(ii) Cost of $1$ q m sheet is $rs2020$
Cost of $5.45$ sq.m, sheet is ?
$=5.45\times 20$
$=Rs.109.$