Subject: General Aptitude · Chapter: Area · Exam: 2005 · Marks: · Difficulty:
The length of a room is double its breadth. The cost of colouring the ceiling at ₹ 25 per sq. m is ₹ 5000 and the cost of painting the four walls at ₹ 240 per sq. m is ₹ 64800. Find the height of the room.
(a)3.5 m
(b)4 m
(c)4.5 m
(d)5 m
Answer
Answer (as printed): C
Explanation
Let the breadth and height of the room be $b$ metres and $h$ metres respectively. Then, length of the room $=(2 b)$ metres. Area of the ceiling $=(2 b \times b) m=\left(2 b^{2}\right) \mathrm{m}^{2}$. $$2 b^{2}=\frac{5000}{25}=200 \Rightarrow b^{2}=100 \Rightarrow b=10 .$$ So, length $=20 \mathrm{m}$, breadth $=10 \mathrm{m}$. Area of 4 walls = [ $2(20$ $+10) \times h] \mathrm{m}^{2}=(60 h) \mathrm{m}^{2}$. $$\therefore \quad 60 h=\frac{64800}{240}=270 \Rightarrow h=\frac{270}{60}=4.5 \mathrm{m} .$$