A box opened at the top is made of wood of thickness 3cm. its external length, breadth and height are respectively 1.48m, 1.16m and 83cm (base = length × breadth). What will be the cost of painting its inner surface at Rs.150 per m² ?

Correct option is A

Thickness of wood = 3 cm
Length = 1.48 m = 148 cm
Breadth = 1.16 m = 116 cm
Height = 8.3 dm = 83 cm
Now,
Inner length = Outer length - twice width = 148 - 6= 142 cm
Breadth = 110 cm
Height = 80 cm [ since it is open box]
Area of inner surface = 2(lb+bh+hl)-lb
=2[142×100+110×80+80×142]−[142×110] = 55940 sq. cm
Cost of painting inner surface = Rs. 150/100×55940/100 = Rs.839.10