An aeroplane is 30 m long and its model is 15 cm long. If the total outer surface area of the model is 150 cm^2, find the cost of painting the outer surface of the aeroplane at the rate of Rs.120 per sq. m. Given that 50 sq. m of the surface of the aeroplane is left for windows.

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Solution

15 cm represents = 30 m

1 cm represents 30/15 = 2m

1 cm^2 represents 2m * 2m = 4 m^2

surface area of the model = 150 cm^2

actual surface area of aeroplane = 1502 2 m^2
= 600 m^2

50 m^2 is left out for window

area to be painted = 600-50 = 550 m^2

cost of painting per m^2 = Rs. 120

cost of painting 550 m^2 = 120*550=Rs. 66000

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