Question

A box is $1m$ long, $60cm$ wide and $40cm$ high. Find the expenditure of colouring its all outer side without its bottom at the rate of $Rs.20$ per square meter.

Answer 1

Length of box $\left(l\right)=1m$

Breadth of box $\left(b\right)=60cm=0.6m$

Height of box $\left(h\right)=40cm=0.4m$

Area of box $=2(lb+bh+hl)=2(1\times 0.6+0.6\times 0.4+0.4\times 1)=2\times (0.6+0.4+0.24)=2\times 1.24=2.48m^2$

Area of bottom $=l\times b=1\times 0.6=0.6m^2$

Therefore,

Cost of colouring per square meter $=Rs.20$

Total expenditure of colouring its all outer side without its bottom $=20\times (2.48-0.6)=2\times 1.88=Rs.3.76$