Question

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

• A. Rs. $100$
• B. Rs. $109$
• C. Rs. $115$
• D. Rs. $110$

Answer 1

The correct option is B Rs. $109$

Length of the box, $l=1.5m$. Breadth of box,$b=1.25m$

Depth of box, $h=65cm=0.65m$

Area of sheet required$=$ Area of cuboid$-$Area of open top

$=2(lb+bh+hl)-lb$

$=lb+2h(b+l)$

$=1.5\times 1.25+2\times 0.65(1.5+1.25)$

$=5.45m^2$

Cost of sheet of $5.45m^2=$Rs. $(5.45\times 20)=$Rs. $109$