## KimJaFo one year ago An hourglass, composed of two identical cones, is 12 cm tall. The radius of each cone is 3 cm. If you want to fill the bottom half of the hourglass 2/3 full of salt, how much salt will you need? Explain the method you would use to find the amount of salt. I just need to know how to solve this, I have completely forgotten.

1. KimJaFo

@mathway

2. KimJaFo

@UsukiDoll

3. DanJS

The volume of the cone is V = (1/3) * pi * r^2 * h

4. DanJS

you want 2/3 of that

5. KimJaFo

Thanks!

6. DanJS

welcome

7. KimJaFo

I got 1017.8, is that correct?

8. KimJaFo

2/3 of that is 678.5 I think.

9. DanJS

$\frac{ 1 }{ 3 }*3.14 * 9 * 12 \approx 113.04$

10. DanJS

2/3 of that is 75.36 cm^3

11. KimJaFo

oh, geez, my math was off.