# Thread: Planet Semirg and Planet Aniram

1. ## Planet Semirg and Planet Aniram

Planet Aniram is similar to Planet Semirg, both of which are perfect sphere. If the ratio of the length of Planet Aniram’s radius to the length of Planet Semirg’s radius is 3:4, then find the volume of Planet Semirg in cubic units if the volume of Planet Aniram is 135 cubic units.

I know how to find the ration, you divide by 3 but I don't know how to find the volume in cubic units.

2. ## Re: Planet Semirg and Planet Aniram

The formula of the volume of a sphere is (4*pi/3)*R^3. You said you know how calculate the ratios. Can you continue from there?

3. ## Re: Planet Semirg and Planet Aniram

Nadeshikol, you need to start showing any work you've been able to do. If you haven't been able to we'll give some hints, but you have to show some effort as well. This refers to your other four posts as well.

-Dan

4. ## Re: Planet Semirg and Planet Aniram

Assume planet Semirg's radius is R. What is its volume, in terms of R? Then planet Aniram's radius if (3/4)R. What is its volume, in terms of R? Divide the two volumes to find their ratio.

5. ## Re: Planet Semirg and Planet Aniram

Originally Posted by topsquark
Nadeshikol, you need to start showing any work you've been able to do. If you haven't been able to we'll give some hints, but you have to show some effort as well. This refers to your other four posts as well.

-Dan
I'm sorry! I will post any work I have done next time.

6. ## Re: Planet Semirg and Planet Aniram

I got 268.16 cubic units as the answer.

Work:

V= 4/3*pi*4^3
V= 4/3*3.14/1=12.56/3
V= about 4.19
V=4.19*4^3
V=268.16

7. ## Re: Planet Semirg and Planet Aniram

Originally Posted by Nadeshiko
I got 268.16 cubic units as the answer.

Work:

V= 4/3*pi*4^3
V= 4/3*3.14/1=12.56/3
V= about 4.19
V=4.19*4^3
V=268.16

8. ## Re: Planet Semirg and Planet Aniram

Originally Posted by votan
Hello! I don' think we have learned this kind of math yet. I mean the V and then a letter at the bottom.

9. ## Re: Planet Semirg and Planet Aniram

Originally Posted by Nadeshiko
Planet Aniram is similar to Planet Semirg, both of which are perfect sphere. If the ratio of the length of Planet Aniram’s radius to the length of Planet Semirg’s radius is 3:4, then find the volume of Planet Semirg in cubic units if the volume of Planet Aniram is 135 cubic units.

I know how to find the ration, you divide by 3 but I don't know how to find the volume in cubic units.
Does not matter what the form of similar simple solids is the volume scales as the cube of any linear dimension. So if the radii are in the ratio $a:b$ the volumes are in the ratio $a^3:b^3$.

The condition that they are both perfect spheres is redundant, that they are similar is sufficient.

.

10. ## Re: Planet Semirg and Planet Aniram

Originally Posted by Nadeshiko
Hello! I don' think we have learned this kind of math yet. I mean the V and then a letter at the bottom.
You used the V in your post of yesterday at 11:14 PM