Question

16. A building has 14 cylindrical pillars, each of diameter 1 m and height 4.5 m. The curved surface of al
the pillars have to be painted leaving 15 cm from top and bottom. Find the cost of painting the pillars
at the rate of 25 per m2.​

Answer 1

${ \huge \purple\maltese \ { \color{maroon}{ \bf \: Question:- }}}$

• A building has 14 cylindrical pillars, each of diameter 1 m and height 4.5 m. The curved surface of all the pillars have to be painted leaving 15 cm from top and bottom. Find the cost of painting the pillars at the rate of 25 per m².

$\huge \pink \maltese \: { \underline{ \color{yellow}{ \bf \: {Given:- }}}}$

• Diameter of pillars are 1m
• Height is 4.5m

$\huge \green\maltese { \underline{ \color{gold}{ \bf \: To \: find : - }}}$

• Cost of painting the pillars

$\huge \red ❃ { \color{blue} \bf \: Solution}$

↦Curved Surface area of cylinder=2πrh

$\bf \: ↦2× \frac{22}{7}× \frac{1}{2}× \frac{45}{10}$

$\bf \: ↦ \frac{99}{7} m²$

$\bf \: ↦The \: CSA \: of \: all \: the \: pillars = 14 × \frac{99}{7}$

$=198m²$

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$\bf \: We \: are \: not \: going \: to \: paint \: the \: pillars \: 15 cm \: from \: the \: top \: and \:bottom$

$\boxed{ \sf{So \: the \: total \: area \: that \: will \: not \: be \: painted \: is =30 cm}}$

$30cm= \frac{30}{10} ^{4} = \frac{3}{10} ^{3} m²$

Area that should be painted is =198- 0.003 m²

=197.997 m²

$\sf \: The \: cost \: is = 25× \frac{197997}{1000}$

= 4949.925 RS

$\bf \: the \: cost \: of \: painting \: is \: \boxed{ \mathfrak{ \green{Rs.4949.925 }}}$

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