Question

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

Answer 1

@Hero @nincompoop

Answer 2

please help

Answer 3

@pooja195, are you going to help?

Answer 4

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

Answer 5

It's getting a bit late for me.

Answer 6

V1 / V2 = (L1 / L2)^3

Answer 7

uhhhhhhh

Answer 8

drawing a blank :(

Answer 9

lol
v=volume
l=length of a dimension

Answer 10

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

Answer 11

gimmie a sec...

Answer 12

ok

Answer 13

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

Answer 14

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

Answer 15

so what would be y?

Answer 16

look
http://prntscr.com/837zqu

Answer 17

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

Answer 18

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

Answer 19

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

Answer 20

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

Answer 21

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

Answer 22

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

Answer 23

understood so far?

Answer 24

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

Answer 25

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)

Answer 26

Is that better?

Answer 27

I got 384

Answer 28

for V2

Answer 29

good how bout V1?

Answer 30

24

Answer 31

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

Answer 32

okay so what do i do after that

Answer 33

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

Answer 34

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

Answer 35

546

Answer 36

good job and that would be our final answer :)

Answer 37

thank you so much

Answer 38

;) no probs ^-^

Answer 39

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