Question

Find the cost of painting the all round outer surface of a box with lid 60 cm long 40 cm wide and30 cm high at 50p per 20cm square

Answer 1

Total surface area of this cuboid= 2(lb+bh+hl)

= 2(60×40 + 40×30 + 30×60)

= 2(2400+1200+1800)

= 2(5400)

= 10800cm²

so,cost to paint 20 cm² = 50 p cost to paint 1 cm²

= 50/20 p cost to paint 10800 cm²

= 50×10800/20

= 27000 p

=27000/100 rs.

= 270 rs.