Question

In a building , 15 cylindrical pillars are to be painted . The diameter and height of each pillar is 48 cm and 7m . Find the cost of the painting if the rate is rs.2 per m²​

Answer 1

Given

• Diameter of pillar = 48cm
• Radius of pillar = 24cm = 0.24m
• Height of pillar = 7m

To find

• Cost of painting the building

Solution

As we know that

→ Curved surface area of pillar

→ 2πrh

→ 2 × 22/7 × 0.24 × 7

→ 10.56 m²

Curved surface area of 15pillars = 10.56 × 15

→ Total cost of painting 15 pillars

→ 10.56 × 15 × 2

→ Rs.316.80

Hence,

• Cost of painting the building is Rs.316.80

Answer 2

${\mathbf {\blue{S}{\underline{\underline{olution:-}}}}}$

$\mathfrak{\underline{AnswEr:-}}$

• The cost of the painting if the rate is Rs.2 per m² = Rs. 316.80

$\mathfrak{\underline{Given:-}}$

• Diameter and height of each cylindrical pillar is 48 cm and 7 m.

$\mathfrak{\underline{Need\:To\: Find:-}}$

• The cost of the painting if the rate is Rs.2 per m² = ?

${\mathbf {\blue{E}{\underline{\underline{xplanation:-}}}}}$

$\sf\underline{\purple{\:\:\: Convert\:into\:m :-\:\:\:}}$

$\sf {Diameter = 48\:cm}$

$\sf {Diameter = \dfrac{48}{100} }$

$\sf {Diameter = 0.48\:m}$

$\sf\underline{\purple{\:\:\: NoW :-\:\:\:}}$

$\sf {Radius = \dfrac{0.48}{2} }$

$\sf {Radius = 0.24\:m}$

$\sf\underline{\green{\:\:\: Here,\:15 \: cylindrical\:pillars\:are\:to\:be\: painted.\:\:\:}}$

$\:\:\:\:\dag\bf{\underline{\underline \pink{Now:-}}}$

$\:\:\:\:\;\:\;\footnotesize\bold{\underline{\underline{\sf{\red{C.S.A \:of \:one \:cylindrical \:pillar = 2\pi rh}}}}}$

$\:\:\:\:\dag\bf{\underline{\underline \blue{So:-}}}$

$\:\:\:\:\;\:\;\footnotesize\bold{\underline{\underline{\sf{\red{C.A.S\:of\:15 \: cylindrical\: pillars \: = \:15 \times 2\pi rh}}}}}$

$\:\:\:\:\dag\bf{\underline \green{Putting\:the\:values:-}}$

$\longrightarrow \sf {15 \times 2 \times \dfrac{22}{7} \times 0.24 \times 7}$

$\longrightarrow \sf {158.4}$

$\:\:\:\:\dag\bf{\underline{\underline \pink{Now:-}}}$

$\:\:\:\:\;\:\;\footnotesize\bold{\underline{\underline{\sf{\red{The\: rate \:of\: painting\: on \:1sq. \:m = Rs\: 2}}}}}$

$\:\:\:\:\dag\bf{\underline{\underline \blue{So:-}}}$

$\sf\underline{\orange{\:\:\: The \:rate\: of \:painting \:on \:158.4\: sq.m = \:\:\:}}$

$\longrightarrow \sf { 158.4 \times 2}$

$\longrightarrow\large\boxed{\sf{\purple{Rs. \:316.80}}}$

$\:\:\:\:\dag\bf{\underline{\underline \green{Hence:-}}}$

• The cost of the painting if the rate is Rs.2 per m² = Rs. 316.80

$\rule{200}{2}$