Question

Hey guy's
HERE IS UR QUESTION:

An iron pipe having outer radius of 4cm is 5m long. its curved surface has to be painted. find the cost of painting it at the rate of Rs. 14per. sq. m
______Thanku​

Answer 1

$\huge\underline{\mathtt{SOLUTION:-}}$

$\sf\underline{\blue{\:\:\:\:Given:-\:\:\:\:\:}}$

$\sf \bullet Radius \:of\: pipe = 4\:cm \:\:or \:\:\:0.04\:m\\ \\ \sf \bullet Height=5m$

• Now we have to find the C.S.A of cylinder

$\boxed{\sf{C.S.A\:of\: cylinder=2\pi rh}}$

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

• Use π=22/7

$\sf\implies C.S.A=2\times \dfrac{22}{7}\times 0.04\times 5\\ \\ \sf\implies C.S.A=\dfrac{2\times 22\times 0.2}{7}\\ \\ \sf\implies C.S.A=\dfrac{8.8}{7}m{}^{2}$

• Now find the cost of painting the C.S.A

$\sf\implies Cost\:of\: painting=\dfrac{8.8}{\cancel7}\times \cancel{14}\\ \\ \sf\implies Cost\:of\: painting= 8.8\times 2\\ \\ \sf\implies Cost\:of\: painting=17.6Rs.$

$\underline{\sf{\blue{\fbox{Cost\:of\: painting=17.6Rs}}}}$

Answer 2

AnSwEr :

• Radius (r) = 4cm = 0.04 m
• Length (l) = 5 m

Formula for C.S.A of Cylinder is :

$\LARGE{\boxed{\boxed{\sf{C.S.A \: = \: 2 \pi rh}}}} \\ \\ \\ : \implies {\rm{C.S.A \: = \: 2 \: \times \: \dfrac{22}{7} \: \times \: 0.04 \: \times \: 5}} \\ \\ \\ : \implies {\rm{C.S.A \: = \: \dfrac{2 \: \times \: 22 \: \times \: 0.2}{7}}} \\ \\ \\ : \implies {\rm{C.S.A \: = \: \dfrac{44 \: \times \: 0.2}{7}}} \\ \\ \\ : \implies {\rm{C.S.A \: = \: \dfrac{8.8}{7}}} \\ \\ {\boxed{\sf{C.S.A \: = \: 1.25 \: m^2}}}$

∴ Curved Surface Area is 1.25 m²

$\rule{200}{2}$

$\Large \star {\boxed{\sf{Cost \: = \: C.S.A \: \times \: Rate}}} \\ \\ \\ : \implies{\rm{Cost \: = \: 1.27 \: \times \: 14}} \\ \\ \\ : \implies {\rm{Cost \: = \: 17.5}} \\ \\ \LARGE{\boxed{\boxed{\sf{Cost \: = \: Rs. \: 17.5}}}}$

∴ Cost of Painting is Rs. 17.5