Question

the length, breadth and height of a room are 1.5,1.25 and 65cm. Find the cost of whitewashing the walls of the room and the ceiling at the rate of ₹20 per meter square​

Answer 1

Answer:

We have a plastic box of

l = length = 15 m

b = width = 1.25 m

h = depth = 65 cm

= 65100 m= 0.65 m (∵ 1 m = 100cm)

Surface area of the box = 2 (lb + bh + hl)

= 2(1.5 x 1.25 + 1.25 x 0.65 + 0.65 x 1.5)

= 2(1.875 + 0.8125 + 0.975) = 2 (3.6625)

= 7.325 m2

(i) Area of the sheet required for making the box

= 7.325 – l x b (∵ BOX is opened at the top)

= 7.325 – 1.5 x 1.25

= 7.325 – 1.875 = 5.45 m2

(ii) A sheet measuring 1 m2 costs = ₹20

∴ Sheet measuring 5.45 m2 costs = ₹20 x 5.45 = ₹109