Question

a cylindical pillar70cm in diameter and 4m heigh is to be cemented all around the curved surface . find the cost of cementing it at the rate of ®32 per m²​

Answer 1

Answer:

Diameter = 70 cm

Radius = Diameter/2

            = 35cm

Height = 4m = 400 cm

CSA = 2πrh

        = 2 × 22/7 × 35 × 400

        = 2 × 22 × 5 × 400

        = 88,000 cm²

88,000 cm² = 8.8 m²

Cost = 8.8 × 32

         = 281.6 RS

Answer 2

$∴Radius \: of \: cylinder=5m \\ \orange{\bold{\underline{\underline</p><p>{Step-by-step\:explanation:}}}} </p><p>$

$\begin{gathered}\begin{gathered}\green{\underline \bold{Given:}} \\ \tt: \implies Height \: of \: cylinder = 21 \: m \\ \\ \tt: \implies Cost \: of \: decorating \:c.s.a = 72930 \: rupees \\ \\ \tt: \implies Cost \: of \: decorating \: 1 \: {m}^{2} = 110.5 \: rupees \\ \\ \red{\underline \bold{To \: Find:}} \\ \tt: \implies Radius \: of \: cylinder = ?\end{gathered}\end{gathered} </p><p>Given:</p><p>$

$:⟹Height \: of \: cylinder=21m \\ </p><p>:⟹Cost \: of \: decorating \: c.s.a=72930rupees \\ </p><p>:⟹Cost \: of \: decorating \: 1m </p><p></p><p> =110.5rupees</p><p>$

$:⟹Radius \: of \: cylinder=?$

• According to given question :

$\begin{gathered}\begin{gathered}\bold{As \: we \: know \: that} \\ \tt: \implies C.S.A \: of \: cylinder = \frac{cost \: of \: decorating \: C.S.A}{ost \: of \: decorating \: 1 \: {m}^{2} } \\ \\ \tt: \implies C.S.A \: of \: cylinder = \frac{72930}{110.5} \\ \\ \tt: \implies C.S.A \: of \: cylinder = 660 \: {m}^{2} \\ \\ \bold{As \: we \: know \: that} \\ \tt: \implies C.S.A \: of \: cylinder = 2\pi rh \\ \\ \tt: \implies 660 = 2 \times \frac{22}{7} \times r \times 21 \\ \\ \tt: \implies 660 = 2 \times 22 \times 3 \times r \\ \\ \tt: \implies r = \frac{660}{44 \times 3} \\ \\ \green{\tt: \implies r = 5 \: m} \\ \\ \green{\tt \therefore Radius \: of \: cylinder \: is \: 5 \: m}\end{gathered}\end{gathered}$

I As we know that

$</p><p> </p><p>:⟹C.S.Aofcylinder=660m </p><p>2$

As we know that

$:⟹C.S.Aofcylinder=2πrh \\ </p><p>:⟹660=2× </p><p>7 \div </p><p>22</p><p> </p><p> ×r×21 \\ </p><p>:⟹660=2×22×3×r</p><p> \\ :⟹r= </p><p>44×3</p><p>660</p><p>$

$:⟹r=5m$

∴Radius of cylinder is 5m

$hope \: its \: help \: u$