Question

Find the cost of painting the all round outer surface of a box with lid 60 cm long,40cm wide and 30cm high at 50p per 20cm

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 = 270 rs.

Answer 2

Dear Student,

● Answer -

Cost of painting = 270 Rs

◆ Explanation -

Total outer surface area of the box is -

TSA = 2 (lb + lh + bh)

TSA = 2 (60×40 + 60×30 + 40×30)

TSA = 10800 sq.cm

Cost to paint outer surface of box is -

Cost of painting = 10800 × 50/20

Cost of painting = 27000 p

Cost of painting = 270 Rs

Hence, cost of painting outer surface of box is Rs. 270.

Thanks dear.