Question

the volume of a metallic cylindrical pipe is 748 cm cube its length is 14 cm and its external radius is 9 cm find its thickness

Answer 1

pi r2 h = 748
22/7×14(81-r2)=748
44(81-r2)=748
4(81-r2)=68
81-r2=17
81-17=r2
64=r2
=>r=8 cm
this means thickness is 9-8=1cm

Answer 2

$<b>Answer</b>$ :

8 cm

$<b>Step - By - Step Explanation</b>$ :

$<b>Given</b>$: Volume of cylindrical pipe = 748 cm³ and it's length is 14 cm and external radius is 9 cm .

$<b>We know that</b>$ : πR²h - πr²h , Where R represents another radius of pipe and r represent original radius of pipe,

$<b>Now, We have</b>$

πR²h - πr²h = 748 cm³

πh (R² - r² ) = 748 cm³

πh [ ( 9)² - (r²) ] = 748 cm³

π.14 [ 81 - r² ] = 748 cm³

14 π [ 81 - r² ] = 748 cm³

π [ 81 - r² ] = 748 ÷ 14

[ 81 - r² ] = 748 ÷ 14 ÷ π

[ 81 - r² ] = 748 ÷ 22/7 × 14

$<b>[ 81 - r² ] = 748 ÷ 44</b>$

[ 81 - r² ] = 17

- r² = 17 - 81

- r² = - 64

r² = 64 cm ²

r = √64 cm

•°• $\sf{\boxed{\boxed{\bf{r\:= \:8 \:cm}}}}$

$<b>Hence , Required thickness ( radius ) of internal cylindrical pipe is 8 cm</b>$