Question

The length breadth and height of a room are 5 metre for metre and 3 may represent a tree find the cost of white washing the walls of the room and the sailing at the rate of rs 7.50 per metre square

Answer 1

$\large{\underline{\underline{ \sf Given:}}}$

• Length of Room = 5m
• Breadth of Room = 4m
• Height of Room = 3m

$\large{\underline{\underline{ \sf Find:}}}$

• Cost of white washing at the rate of Rs 7.50/m²

$\large{\underline{\underline{ \sf Solution:}}}$

we, know that

$\boxed{\rm{\dashrightarrow C.S.A = 2(l + b)h}}$

where,

• Length, l = 5m
• Breadth, b = 4m
• Height, h = 3m

So,

$\rm{\dashrightarrow C.S.A = 2(l + b)h}$

$\rm{\dashrightarrow C.S.A = 2(5 + 4)3}$

$\rm{\dashrightarrow C.S.A = 6(9)}$

$\rm{\dashrightarrow C.S.A = 54 {m}^{2} }$

$\rm{\therefore C.S.A = 54 {m}^{2} }$

$\rule{300}{2}$

Now,

$\boxed{\rm{\dashrightarrow Area = l \times b}}$

where,

• Length, l = 5m
• Breadth, b = 4m

So,

$\rm{\dashrightarrow Area = l \times b}$

$\rm{\dashrightarrow Area = 5 \times 4}$

$\rm{\dashrightarrow Area = 20 {m}^{2} }$

$\rm{\therefore Area = 20 {m}^{2} }$

$\rule{300}{2}$

:= Total Surface Area of Room = C.S.A + Area

:= Total Surface Area of Room = 54 + 20

:= Total Surface Area of Room = 74m²

Since, Cost of white washing 1m² = Rs 7.50

So, cost of white washing 74m² = 74×7.50

= Rs 555

$\rule{300}{2}$

$\underline{\mathfrak{\therefore Cost \: of \: white \: washing = Rs555 }}$