Please help me with the following question

Question

Two cylindrical jars A and B have diameters 12cm and 18cm respectively. Initially, cylinder A contains water to a depth of 21cm and cylinder B is empty. If all the water from cylinder A is poured into cylinder B find the height of the water in cylinder B.

Answer 1

Hi Kevin,

 

Using the formula for volume of a cylinder: V=πr²h.

 

So, for cylinder A calculate the volume of water at a height of 21cm (r=6cm or 1/2 the diameter).

 

V_a=π(36)(21) cu. cm.

 

If we pour that amount of water into cylinder B we have the equation:

 

π(36)(21) = π(81)(h)  --where the 81 is the radius of cylinder B squared. Now solve for h.

 

h = π(36)(21)/ π(81)   --the "pi" cancels out and we can reduce to 28/3 cm.