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Answer 1

Step-by-step explanation:

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Answer 2

GIVEN :-

cylinder

• Given diameter of solid cylinder is 2 cm.

• Radius of solid cylinder, r=1 cm.

hollow cylinder

• Length of hollow cylinder, H=15 cm

• External diameter =20 cm

• External radius =10 cm

• Thickness =0.25 cm

TO FIND :-

• length of solid cylinder

SOLUTION :-

we know that volume of solid cylinder = volume of hollow cylinder

hence ,

volume of solid cylinder :-

$\implies \boxed{\rm {volume \:of \: solid \: cylinder =\pi {r}^{2} h }}$

$\implies \rm {volume \:of \: solid \: cylinder =\pi {(1)}^{2} h } \times - - \: eq1$

now volume of hollow cylinder :-

$\implies \boxed{\rm {volume \:of \: hollow\: cylinder =\pi h({r _{1} }^{2} - \:{r _{2} }^{2} )}}$

now,

Thickness = R - r

Thickness = R - r 0.25 = 10 - r

Thickness = R - r 0.25 = 10 - r Internal radius = 9.75cm

$\implies \rm {\pi (15)(({10 })^{2} - \:{(9.75) }^{2} )}$

$\implies \: \rm {\pi (15)(100 - \:95.0625) - - \: eq2}$

now , volume of solid cylinder = volume of hollow cylinder

hence , from eq 1 and 2

$\implies \rm {{(1)}^{2} h =(15)(100 - \:95.0625)}$

$\implies \rm {h =(15)(4.9375)}$

$\implies \rm {h =74.06 \: cm}$

hence,

$\implies \boxed { \boxed{\rm {length \:of \: cylinder = 74.06 \: cm} }}$