Question

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A 5-foot tall student stands 10 feet away from the lens of a camera. The film of the camera is 3 inches away from the lens.

A 5 ft tall student is standing 10 feet away from the lens of a camera; behind the lens of the camera is shown the film of the camera, 3 inches away from the lens.

What is the height of the film?
Answer

0.2 inches

0.7 inches

1.2 inches

1.5 inches

Answer 1

Was there a picture included with this?

Answer 2

yes. one second

Answer 3

What exactly is the topic of study for your class?

Answer 4

meaning? Its geometry and that lesson was about similar triangles

Answer 5

That's what I needed to know

Answer 6

kk

Answer 7

Okay, I figured out what it was, but the explanation is kind of whacky

Answer 8

You're supposed to create a proportion relating the two triangles by setting height of the person to the height of the film equal to the length of the person from the lens to the length of the film from the lens.

Answer 9

right. I can get there but whats next?

Answer 10

do I cross multiply?

Answer 11

Next you cross multiply, then solve for x.

Answer 12

wait a second....

Answer 13

We need to convert feet to inches.

Answer 14

oh lord. I didnt notice that......

Answer 15

Yeah, I just realized it myself.

Answer 16

1/40 = 5/x ??

Answer 17

x = 200.........right?

Answer 18

So after converting ft to inches, you get

60 for the height of the person
120 the person's distance from the lens

So replacing those in the proportion you get:

\[\frac{60}{x}=\frac{120}{3}\]

Answer 19

Just kidding! geez my brain is fried

Answer 20

\[\frac{60}{x}=40\]

Answer 21

60 = 40x
6 = 4x
6/4 = x
2/3 = x

Answer 22

in inches, not feet

Answer 23

60/x = 40
x = 40/60
x = 4/6
x = 2/3
x = .67?

Answer 24

Yes

Answer 25

.7 inches. Yay!! thank you!

Answer 26

wait, lol

Answer 27

uh oh.......lol

Answer 28

I think I did that backwards

Answer 29

3/2 = x

Answer 30

60 = 40x
6 = 4x
6/4 = x
3/2 = x

Answer 31

1.5??

Answer 32

Yes

Answer 33

thanks!

Answer 34

Funny thing is, even if you don't convert, you still get 1.5
I find that very strange

Answer 35

ha

Answer 36

lol