Question

(b) The amount of metal in a hollow cylinder
with height 14 decimetre and external
diameter 5 decimetre is 42.24 cubic
decimetre. Find the thickness of the
cylinder
>​

Answer 1

given,

height= 14 decimeter= 1.4m

diameter= 5 decimeter= 0.5m

(∴radius= 0.25 as r=d/2)

volume= 42.24cm3

solution,

let external thickness be x

so, total radius is (0.25+x)

(as total radius-= radius+thickness)

now,

volume of cylinder= π r2 h=  π (0.25+x)2 (1.4)

42.24= π (0.25+x)2 (1.4)

9.6= 0.0625+x2+0.5x

9.5375-x2-0.5x=0

(let us assume 9.5375 as 9.5 for convenience of our calculation)

so, x2+0.5x-9.5= 0

bro now u can solve it by mid term split, the positive value would be your answer as radius can't come in negative :))

thank you!! :D