janessia 2 years ago Find the volume of a cone with radius 6 m and height 20 m. Choose one answer. a. 720π m^3 b. 240π m^3 c. 120π m^3 d. 40π m^3

1. janessia

@jim_thompson5910 i got 753 and i did all the steps but no right answer... help me?

2. jim_thompson5910

Area of the base = ???

3. phi

Did you use $V= \frac{1}{3} \pi r^2 h$

4. janessia

@jim_thompson5910 sorry i had to run some errands for my mom but the area of the base is 113.04

5. janessia

@jim_thompson5910 am i right?

6. jim_thompson5910

yes

7. jim_thompson5910

now multiply that with the height

8. janessia

2260.8

9. jim_thompson5910

then divide by 3

10. janessia

i still got 753.6!

11. janessia

thats wrong!

12. jim_thompson5910

ok which matches to which answer

13. jim_thompson5910

i know, each answer has a pi in it

14. jim_thompson5910

one of those answers is roughly equal to 753.6

15. janessia

720

16. janessia

?

17. jim_thompson5910

no, try doing the calculations without 3.14 and use pi instead

18. janessia

k

19. janessia

i really dont know i did and i got 753.98223687 this time

20. phi

when you find the area using $\pi r^2$ leave pi in. do not use 3.14 you get $36 \pi$

21. janessia

i dont have my graphing calc right now so im using a scientific one right now

22. janessia

but ohk yes i got 36

23. phi

V= 1/3 pi r^2 h if you leave the pi to one side: $\pi (\frac{1}{3} 36 \cdot h )$ just figure out the stuff in the parens

24. janessia

i got 240 woowww how'd yo do that... how was i getting 753?

25. janessia

I got B for this is that right? Find the volume of a square pyramid with base edges 4 ft. and height 15 ft. Choose one answer. a. 20 cu. ft b. 80 cu. ft c. 240 cu. ft d. 60 cu. ft

26. phi

the answer is $240 \cdot \pi$ 240 times pi if you replace pi with 3.14159... you get 753. with lots of decimals people just write it 240 pi and if someone wants the exact number, they can multiply it out themselves.

27. phi

Yes to b. 80 cu. ft

28. janessia

oh ohk thanks a lot can you check my answer above?

29. janessia

thanks :)