Question

An open cuboidal box has dimensions $25cm\times 10cm\times 25cm$. Find the cost of painting the box from outside if the painting cost is ₹ $2/c{m}^2$.

Answer 1

Since, the box is open, there are only five faces instead of six as shown in the figure:

So, there are four walls and one base.

Area of two walls with length, $25cm$ $=2\times (25\times 25)=1250c{m}^2$

Area of two walls with length, $10cm$ $=2\times (10\times 25)=500c{m}^2$

Area of the base $=25\times 10=250c{m}^2$

Total surface area $=$ Area of four walls $+$ Area of base $=1250+500+250=2000c{m}^2$

Cost of painting is ₹ $2/c{m}^2$

So, total cost of painting the box from outside $=2000\times 2=$
₹$4000$