The volume of a brick is 3000 cm⊃3; and its dimensions are in the ratio 3 : 2 : 4. If its entire surface is painted at 50 paisa per cm⊃2;. The cost will be (in Rs.)
Answer: D
Let the length of the brick be 3X, breadth of the brick be 2X and height of the brick be 4X.
Given: Volume of a brick is 3000 cm⊃3;
WKT, Volume of brick = l x b x h
Volume of brick = 3X*2X*4X
3000 = 24X⊃3;
X = 5
Length of the brick = 3X = 3(5) = 15 cm
Breadth of the brick = 2X = 2(5) = 10 cm
Height of the brick = 4X = 4(5) = 20 cm
WKT, Total surface area of brick = 2(lb + bh + hl)
Total surface area of brick = 2[(15 x 10) + (10 x 20) + (20 x 15)]
= 2[150 + 200 + 300]
= 1300⊃2;
The cost = 1300 x (50/100) = Rs. 650.