edited by
904 views
1 votes
1 votes

The length, breadth and height of a room are in the ration $3:2:1.$ If the breadth and height are halved while the length is doubled, then the total area of the four walls of the room will

  1. remain the same.
  2. decrease by $13.64\%$
  3. decrease by $15\%$
  4. decrease by $18.75\%$
  5. decrease by $30\%$
edited by

1 Answer

1 votes
1 votes

Let  l = 3x, b = 2x and h = x

Area of 4 walls = 2(lh + bh) = 2(3x2 + 2x2) = 10x2

New dimensions are as follows,

l' = 2l = 6x, b' = $\frac{b}{2}$ = x and h' = $\frac{h}{2}$ = 0.5x

Area of 4 walls = 2(l'h' + b'h') = 2(6x * 0.5x + x * 0.5x) = 7x2

So we can see that area has decreased.

% decrease  = $\frac{10x^{2} - 7x^{2}}{10x^{2}}$ * 100 = 30%

Option 5 is correct

Answer:

Related questions

0 votes
0 votes
0 answers
3
go_editor asked Dec 28, 2015
446 views
An equilateral triangle $\text{BP}$ is drawn inside a square $\text{ABCD}.$ What is the value of the angle $\text{APD}$ in degrees?$75$$90$$120$$135$$150$
1 votes
1 votes
1 answer
4
go_editor asked Dec 28, 2015
832 views
If $\log_y x = a \cdot \log_z y = b \cdot \log_x z = ab$ then which of the following pairs of values for $(a,b)$ is not possible?$-2, 1/2$$1,1$$0.4, 2.5$$\pi, 1/\pi$$2,2...
0 votes
0 votes
1 answer
5
go_editor asked Dec 28, 2015
605 views
The number of employees in Obelix Menhor Co. is a prime number and is less than $300.$ The ratio of the number of employees who are graduates and above, to that of employ...