## anonymous one year ago An hourglass consists of two sets of congruent composite figures on either end. Each composite figure is made up of a cone and a cylinder, as shown below: Each cone of the hourglass has a height of 18 millimeters. The total height of the sand within the top portion of the hourglass is 54 millimeters. The radius of both cylinder and cone is 8 millimeters. Sand drips from the top of the hourglass to the bottom at a rate of 10π cubic millimeters per second. How many seconds will it take until all of the sand has

1. anonymous

68.3 38.4 268.8 230.4

2. anonymous

I think its 268.8

3. anonymous

@Marcorie @misssunshinexxoxo @jdoe0001 @dan815

4. anonymous

is their a pic?

5. anonymous

Yes

6. anonymous

7. anonymous

8. anonymous

lol

9. anonymous

sorry im not really sure try asking someone else i tried it and got the wrong answer

10. anonymous

Thats okay :)

11. anonymous

@Anon.

12. anonymous

13. anonymous

i agree with u @CaptainLlama49

14. anonymous

Cool I just might have it right

15. Astrophysics

Well you have the volume of the cylinder which is $V = \pi r^2 h$ and cone is $V_c = 1/3 \pi r^2h$ we are given that the height of the hourglass is 18 mm, and the total height within the top portion of the hour glass is 54 mm. It also tells us the radius of the cylinder and the cone is 8mm. So we just need to find the total volume, using the formulas above and once we have that we can just divide by $10 \pi~ mm^3$ to figure out the time it will take the sand to be at the bottom I assume?

16. anonymous

yes

17. Astrophysics

Yeah, so you should be able to figure out the rest

18. anonymous

I got 268.8

19. anonymous

Is that correct

20. Astrophysics

Well lets find the volume of the cone and cylinder first, what did you get?

21. anonymous

268.8

22. anonymous

@Astrophysics

23. Astrophysics

Well I don't really feel like doing the whole problem, I gave you the process you can plug in the numbers and check.

24. anonymous

100% YES!

25. Astrophysics

Haha, so it was right? :)

26. anonymous

Yep

27. Astrophysics

Nice work

28. anonymous

Thank you :)