Question

The length, breadth and height of a room are in the ratio 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. Decrease by 13.6% 2. Decrease by 15% 3. Decrease by 30% 4. Decrease by 18.75%

Answer 1

$\huge\mathfrak{Answer:}$

$Given:-$

$l : b : h = 3 : 2 : 1$

Let,

$h = 10, b = 20, l = 30$

$Now,$

$Area$ $= 2 (l + b) h$

$= 2 ( 30 + 20) 10$

$= 2 (50)10$

$= 2 (500)$

$= 1000$

$Now,$

After those adjustments in the measurements,

$We\: get,$

$l = 60, b = 10, h = 5$

$Now,$

$Area$ $= 2(l + b) h$

$= 2(60 + 10) 5$

$= 2(70) 5$

$= 2 (350)$

$= 700$

Now,

Percentage Decrease

$= \frac{1000 - 700}{1000} \times 1000$

$= \frac{300}{1000} \times 1000$

$= 300$

Now,

$= \frac{300 \times 100}{1000}$

$= \frac{30000}{1000}$

$= 30\%$

Therefore,

Correct option 3) Decrease by 30%

$\huge{Be\:Brainly}$❤️

Answer 2

hey

here is answer

Given:-

l : b : h = 3 : 2 : 1

Let, 

h = 10, b = 20, l = 30

Now

Area = 2 (l + b) h

= 2 ( 30 + 20) 10

= 2 (50)10 

= 2 (500)

= 1000

Now,

After those adjustments in the measurements, 

l = 60, b = 10, h = 5

Now,Now, 

AreaArea = 2(l + b) h

= 2(60 + 10) 5

= 2(70) 5

= 2 (350)

= 700

Now,

Percentage Decrease 

$\begin{lgathered}= \frac{1000 - 700}{1000} \times 1000 \\\end{lgathered}$

$\begin{lgathered}= \frac{300}{1000} \times 1000 \\\end{lgathered}$

= 300=300 

Now, 

$= \frac{300 \times 100}{1000}$

$\begin{lgathered}= \frac{30000}{1000} \\\end{lgathered}$ 

=30% 

hope it helps

thanks