Take the 2-minute tour ×
Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. It's 100% free, no registration required.

This is a question that i was not able to solve, help about it is highly appreciated.

The radii of the bases of a cylinder and a cone are 3:4 and their heights are in the ratio 2:3, what is the ratio of their volumes?

share|improve this question

2 Answers 2

up vote 1 down vote accepted

You have a cylinder with height $h_1$ and radius of base $r_1$. Then the volume is $V_1 = h_1\pi r_1^2$.

You have a cone with height $h_2$ and radius of base $r_2$. The volume is $V_2 = \frac{1}{3}h_2\pi r_2^2$

Now you are told that $$\begin{align} r_1 &= \frac{3}{4}r_2\quad\text{and} \\ h_1 &= \frac{2}{3}h_2. \end{align} $$ Use this to find $$ \frac{V_1}{V_2}. $$

share|improve this answer
    
Slightly incorrect - aayush is told that the ratio of the radii of the bases is 3/4. So it should be $B_1 = (3/4)^2 B_2$. –  Glen O Mar 22 '13 at 14:32
    
That is, unless it's a typo. –  Glen O Mar 22 '13 at 14:32
    
@GlenO: You are right. I misread the question. I updated the answer. –  Thomas Mar 22 '13 at 14:43

since you have just to compute the ratio of their volumes and you have the ratio of the bases and heights, you may just choose convenient values for the latter.

Take a cylinder with base 3 cm and height 2 cm and a cone with base 4 cm and height 3 cm, and do the math.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.