## A community for students. Sign up today

Here's the question you clicked on:

## anonymous one year ago The two square pyramids are similar. Find the total volume of both pyramids if the ratio of their surface areas is 9/16. A. 545 inches cubed B. 546 inches cubed C. 554 inches cubed D. 564 inches cubed

• This Question is Closed
1. anonymous

2. anonymous

@Hero @nincompoop

3. anonymous

please help

4. Hero

@pooja195, are you going to help?

5. anonymous

I really need desperate help. I'm horrible at ratios and anything having to do with similar figures.

6. Hero

It's getting a bit late for me.

7. pooja195

V1 / V2 = (L1 / L2)^3

8. anonymous

uhhhhhhh

9. anonymous

drawing a blank :(

10. pooja195

lol v=volume l=length of a dimension

11. anonymous

i know that i just dont know how to put the numbers and that formula together

12. pooja195

gimmie a sec...

13. anonymous

ok

14. pooja195

Let's use volume formula of pyramid V = 1/3 * base area * height

15. pooja195

V = 1/3 * base area * height V1 = 1/3 * (x)^2 * 6 V2 = 1/3 * (12)^2 * y

16. anonymous

so what would be y?

17. pooja195
18. pooja195

x is the side length of the base of the small pyramid y is the height of the larger pyramid

19. anonymous

okay so how do i figure out the y then, im sorry i sound dumb im just confused. i know the formula but how do i do it wen i dont know the y

20. pooja195

lol you're not dumb! :) Here see if you understand this :) Let's use volume formula of pyramid Volume = 1/3 * base area * height Given: V1 = 1/3 * (x)^2 * 6 V2 = 1/3 * (12)^2 * y We can find the scale factor A1 / A2 = (L1 / L2 ) ^2 = 9/16 L1 / L2 = √ 9/16 = 3/4

21. anonymous

ok so the scale factor is 3/4. what's next

22. pooja195

lol you're not dumb! :) Here see if you understand this :) Let's use volume formula of pyramid Volume = 1/3 * base area * height Given: V1 = 1/3 * (x)^2 * 6 V2 = 1/3 * (12)^2 * y We can find the scale factor A1 / A2 = (L1 / L2 ) ^2 = 9/16 L1 / L2 = √ 9/16 = 3/4 L1 = 3/4 * L2 Let L2 = y , then L1= 3/4* L2 x= 3/4*y V1 = 1/3 * (3/4 *y ) * 6 V2 = 1/3 * (12)^2 * y

23. pooja195

The scale factor is 3/4 to go from the bigger pyramid to the smaller pyramid

24. pooja195

understood so far?

25. anonymous

No... i'm sorry. everything is confusing me..

26. pooja195

We can find the scale factor A1 / A2 = (L1 / L2 ) ^2 = 9/16 L1 / L2 = √ 9/16 = 3/4 The scale factor is 3/4 to go from the bigger pyramid length dimension to the smaller pyramid length dimension. The scale factor is 4/3 to go from the smaller pyramid length dimension to the bigger pyramid length dimension. V1 = 1/3 * (3/4 * 12) ^2 * 6 V2 = 1/3 * (12)^2 * (6 * 4/3)

27. pooja195

Is that better?

28. anonymous

I got 384

29. anonymous

for V2

30. pooja195

good how bout V1?

31. anonymous

24

32. pooja195

Not quite... V1 = 1/3 * (3/4 * 12) ^2 * 6= 162

33. anonymous

okay so what do i do after that

34. anonymous

if you don't mind kind of fast forwarding a little bit im on a timed assignment. i dont mean to sound rushy :(

35. pooja195

dont worry :-) we're almost done! :D 384+162=?

36. anonymous

546

37. pooja195

good job and that would be our final answer :)

38. anonymous

thank you so much

39. pooja195

;) no probs ^-^

40. pooja195

$$~~~~~~~~~~~~~~~~~~~~~~~~~~\Huge{\color{red}{\heartsuit}\color{orange}{\bigstar}\color{yellow}{\heartsuit}\color{green}{\bigstar}\color{blue}{\heartsuit}\color{purple}{\bigstar}\color{hotpink}{\heartsuit}}$$$$\Huge\bf\color{#FF0000}W\color{#FF4900}e\color{#FF9200}l\color{#FFDB00}c\color{#FFff00}o\color{#B6ff00}m\color{#6Dff00}e\color{#24ff00}~\color{#00ff00}t\color{#00ff49}o\color{#00ff92}~\color{#00ffDB}O\color{#00ffff}p\color{#00DBff}e\color{#0092ff}n\color{#0049ff}S\color{#0000ff}t\color{#2400ff}u\color{#6D00ff}d\color{#B600ff}y\color{#FF00ff}!$$$$~~~~~~~~~~~~~~~~~~~~~~~~~~\Huge{\color{red}{\heartsuit}\color{orange}{\bigstar}\color{yellow}{\heartsuit}\color{green}{\bigstar}\color{blue}{\heartsuit}\color{purple}{\bigstar}\color{hotpink}{\heartsuit}}$$$$\Large\bf\color{Lime}{Please,\ don't\ hesitate\ to\ ask\ questions!}$$$$\Large\bf\color{magenta}{We're\ here\ to\ help!}\Large\color{magenta}{\ddot\smile}$$

#### Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy