Question

The external and internal radius of a hollow right circular cylinder of height 13 cm are 6.75 cm and 5.2 cm respectively. If it is melted to form a solid cylinder of height , half of the original cylinder , find the radius of tje cylinder

Answer 1

Answer:

Step-by-step explanation:

Given  

The external and internal radius of a hollow right circular cylinder of height 13 cm are 6.75 cm and 5.2 cm respectively.  

We know that

Volume of a cylinder = πr1^2 h – πr2^2h

                                   = πh(r1^2 – r2^2)

                                   = πh(6.75 + 5.2)(6.75 – 5.2)

                                   = 22/7 x 13 x 11.95 x 1.55

Now vol = πr^2h

              = 22/7 x 13 x 11.95 x 1.55

So r^2 x 13/2 = 13 x 11.95 x 1.55 (according to question)

We get r^2 = 37.045

          r = 6.086 cm