Question

A cylindrical Metallica pipe is 14cm long. The diffrence Between the out side and inside surface is 44cm square. if the pipe is made up of 99CU cm of metal find the outer and inner radii of the pipe
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Answer 1

HAY!!
DEAR USER-

Let the outer and inner radii be R cm and r cm respectively .
Also, it is given that h=14cm.
Than, outside surface area=
$(2\pi \: rh)$
= (2×22/7×R×14)cm²

=>(88R)cm²

inside surface area =(2×22/7×r×14)cm²

=> (88r)cm²

(88R-88r) =44

=>88(R-r) =44

=>(r-r) =1/2...................(I)

External volume =>(22/7×R²×14)cm³=(44R²)cm³

Volume of metal =>

External volume - Internal volume

=> (44R²-44r²)cm³=44(R²-r²)cm³

=> 44(R²-r²)=99/44

=> (R²-r²)=9/4.......................(II)

On Dividing (ii) by (I) we get : (R+r)=9/2.......(III)

On solving (I) and (III) we get : R=5/2
and r =2.


Hence, the outer radius =2.5cm and the inner radius =2cm

I hope it's help you