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Similar solids, volumes 27 and 64, small height 6, find the large…

Step by step, with the reason for every step · Similar shapes and solids · Geometry

Step by step

The question

Question: two similar solids have volumes 27 and 64, and the small height is 6: find the large height.

volumes 27 and 64, small height = 6

1 Volume factor

The large volume divided by the small one: 64/27.

That is k cubed.

volume factor = 6427

2 Length scale factor

To go back from k cubed to k, we take the cube root: 4/3.

k = ∛(6427) = 43
4/3 × 4/3 × 4/3 = 64/27

Careful!

64/27 is the volume factor.

Lengths grow less: by its cube root.

Careful: not k = 64/27 ✗

3 Use it

6 times 4/3 is 8.

large height = 6 × 43 = 8

4 Check

Let's check: the large height divided by the small one is 4/3, the scale factor.

So it is right!

8 ÷ 6 = 4/3 = k

Let's look back.

First: volume factor.

Then: length scale factor.

Then: use it.

Last: check.

Answer
large height = 6 × 43 = 8

Your turn

Try this one yourself, then check:

volumes 27 and 64, small height = 3
Show the answer
large height = 4

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