Question

The length, breadth and height of a room are 5 m, 4 m and 3 m respectively. Find the cost of white washing the walls of the room and the ceiling at the rate of Rs. 7.50 per m2.​

Answer 1

$\bf \red { \underline{ \underline{Given}}}$

• Length, l = 5m

• Breadth,b = 4m

• Height, h = 3m

• the ceiling at the rate of Rs. 7.50 per m².

$\bf \red { \underline{ \underline{To \: find \: out }}}$

Find the cost of white washing the walls of the room.

$\bf \red { \underline{ \underline{Solution }}}$

Area to be white washed = Area of 4 wall + Area of ceiling.

$\rightarrow \: 2h(l + b) + l \times b$

$\bigstar \: \green{ Putting \: the \: values}$

$\rightarrow \: 2 \times 3(5 + 4) + 5 \times 4$

$\rightarrow \: 2 \times 3 \times 9 + 5 \times 4$

$\rightarrow \: 54 + 20$

$\rightarrow \: 74m \: {}^{2}$

Now,

$Cost \: of \: White \: washed = 74 \times 7.50$

$\implies \: 74 \times \frac{750}{100}$

$\implies \purple{555}$

Answer 2

$\huge\mathfrak\blue{Answer:-}$

Given:

The length, breadth and height of a room are 5 m, 4 m and 3 m respectively.

To Find:

The cost of white washing the walls of the room and the ceiling at the rate of Rs. 7.50 per m^2.

Solution:

Length = 5m

breadth = 4m

height = 3m

lateral surface area + length × breadth

=2 × ( l + b ) × h + l × b

=2 × (5+4) × 3 + 5 × 4

=2 × 9 × 3 + 20

       

=54 + 20

             

=74m^2

Now Cost of white washing 1m = Rs 7.5

Cost of 74m= 7.5 × 74 = Rs 555.

Hence the cost of of white washing the walls of the room and the ceiling at the rate of Rs. 7.50 per m^2 is Rs 555.