SOLUTION: Two circular metal disc of radii 3.3cm and 5.6cm are melted down and cast into a single circular disc of the same thickness. Find the radius of this disc.

Algebra ->  Test -> SOLUTION: Two circular metal disc of radii 3.3cm and 5.6cm are melted down and cast into a single circular disc of the same thickness. Find the radius of this disc.       Log On


   

Question 1205012: Two circular metal disc of radii 3.3cm and 5.6cm are melted down and cast into a single circular disc of the same thickness. Find the radius of this disc.
Answer by ikleyn(52835) About Me  (Show Source):
You can put this solution on YOUR website!
.
Two circular metal highlight%28cross%28disc%29%29 disks of radii 3.3cm and 5.6cm are melted down and cast
into a single circular disc of the same thickness. Find the radius of this disc.
~~~~~~~~~~~~~~~~~~~~~ 

Equate the volumes

    pi%2A3.3%5E2%2Ah + pi%2A5.6%5E2%2Ah = pi%2Ar%5E2%2Ah.


where "h" is the common thickness.  

Cancel common factor  pi%2Ah.  Get

    3.3%5E2+%2B+5.6%5E2 = r%5E2

    42.25 = r%5E2

    r = sqrt%2842.25%29 = 6.5 cm.


ANSWER.  The radius of the resulting disk is 6.5 cm.

Solved.

-----------------

The lesson to learn from this my solution is the Law of mass conservation.