Math, asked by lakshmipsanthosh07, 4 months ago

a class room is 7 m long, 6 m broad and 3.5 m high doors and windows occupy an area of 17 square m what is the cost of white washing wallls at the rate of 1.5 per square m​

Answers

Answered by violet14
4

the cost is Rs. 174

hope u understand it

:)

Attachments:
Answered by SuitableBoy
28

{\huge{\underline{\underline{\bf{\star Question }}}}}

Q - A class room is 7 m long , 6 m broad and 3.5 m high doors and windows occupy an area of 17 square m . What is the cost of white washing the walls at the rate of 1.5 square m ?

{\huge{\underline{\underline{\bf{ Answer \checkmark}}}}}

{\large{\underline{\rm{☆ Given}}}}

  • Length = 7 m
  • Breadth = 6 m
  • Height = 3.5 m
  • Area of doors & windows = 17 m²
  • Rate of whitewashing = 1.5/m²

{\large{\underline{\rm{☆ To\;Find}}}}

  • Total Cost of whitewashing = ?

{\huge{\underline{\rm{☆ Solution}}}}

First , finding the total area to whitewash -

We know , that only 4 walls are to be whitewashed , except door and windows ..

so ,

 \boxed{ \rm \: area _{whitewash} = area _{4 \: walls} - area _{doors \: and \: windows}}

 \mapsto \rm \: ar _{whitewash}  = 2(l + b) \times h  -  17 {m}^{2}

  \mapsto \rm \: ar _{whitewash} = 2 \times 3.5(7 + 6)  -  17 \:  {m}^{2}

 \mapsto \rm \: ar _{whitewash} = 7 \times 13  - 17 \:  {m}^{2}

 \rm \mapsto \: ar _{whitewash} = 91 - 17 \:  {m}^{2}

 \mapsto \boxed{ \rm \: area _{whitewash} = 74 \:  {m}^{2} }

Now ,

Finding the Total Cost now ..

 \boxed{ \rm \: cost = rate \times area}

 \mapsto \rm \: cost =  \frac{1.5}{  \cancel{{m}^{2} }}  \times 74 \:   \cancel{{m}^{2} } \\

 \mapsto \rm \: cost \:  = 1.5 \times 74 \: rupees

 \mapsto \boxed{ \rm \:cost  = 111 \: rupees}

So ,

The cost of whitewashing would be 111 Rs .

________

{\large{\underline{\rm{☆ Know\;More:-}}}}

  •  \sf \: area \: of \: 4 \: walls = 2(l + b) \times h
  •  \sf \: cost \:  = rate \times area
  •  \sf \: tsa = 2(lb + bh + lh)
  • Area is always in unit square (u²)

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