## Unofficialllyy one year ago Could someone check if I am on the right track? WILL FAN AND MEDAL!

1. Unofficialllyy

The holding tanks are congruent in size, and both are in the shape of a cylinder that has been cut in half vertically. The bottom of the tank is a curved surface. What is the volume of both tanks if the radius of tank #1 is 15 feet and the height of tank #2 is 120 feet? You must explain your answer using words, and you must show all work and calculations to receive credit. So I know I have to use the formula for the volume of a cylinder which is $V=\Pi r^2h$ Since it's given that the radius is 15 and the height is 120, I plugged them into the formula. $V=\Pi (15)^2(120)$ Is this right so far?

2. Unofficialllyy

@campbell_st

3. campbell_st

its makes sense to me... the congruent tanks form a cylinder, radius 15 and height 120

4. Unofficialllyy

Then I do 15^2 which is 225. Then I multiply 225 and 120 to get 2700. Then I multiply pi and 2700 to get 2700pi, or in decimal form 8482.30016469

5. Unofficialllyy

But it says it is cut in half vertically, so do I divide by 2?

6. Unofficialllyy

@campbell_st

7. campbell_st

well I read the question as the tanks are congruent halves... |dw:1437263162103:dw|

8. Unofficialllyy

But I am finding the volume of the whole cylinder first, and then dividing by 2.

9. Unofficialllyy

I should get the same answer, right?

10. campbell_st

well the way I read it, the 2 tanks make the whole... sorry I can't help much more that that... so I'd expect that the volume is $V = \pi \times 15^2 \times 120$

11. Unofficialllyy

Okay thank you

12. Unofficialllyy

@jim_thompson5910 could you see if you could help too?

13. campbell_st

the question asks for the volume of 1 tank so you could find the volume of the whole, divide it by 2.... and say that tank has a volume = x, since tank 2 is congruent, the combined volume is V = 2x

14. Unofficialllyy

Right. So my final answer after dividing by 2 is 4241.15008234

15. Unofficialllyy

Then I have to round to the nearest whole number

16. Unofficialllyy

Wait nevermind I don't have to round.

17. campbell_st

so reading the question again, the 2 tanks are like feeding troughs |dw:1437263554473:dw|

18. Unofficialllyy

I feel like i have the right answer, i just want to make sure lol :)

19. Unofficialllyy

but then it says what is the volume of BOTH tanks

20. Unofficialllyy

so do i even need to divide by 2?

21. jim_thompson5910

V = pi*r^2*h V = pi*15^2*120 V = 27,000pi exact volume of the two tanks put together, to form one complete cylinder, is 27000pi

22. jim_thompson5910

there's no need to divide by 2. Imagine gluing them together to form one cylinder

23. Unofficialllyy

so my answer would be 8482.30016469

24. Unofficialllyy

wait no hang on

25. Unofficialllyy

V=84823.00164692

26. Unofficialllyy

I was doing 2700 not 27000

27. jim_thompson5910

yeah you were missing a 0

28. Unofficialllyy

Thank you :)

29. jim_thompson5910

no problem