Joe and the lamp post

[Brent@GMATPrepNow]

When Joe stands 12 meters away from a lamp post, his shadow is 3 meters long. If the lamp post is 9 meters high, what is Joe’s height in meters?
A) 13/8
B) 5/3
C) 9/5
D) 16/9
E) 9/4

[cramya]

12 / 3 = 9/x

x=9/4 = 2.25

Choose E)

[vivek.kapoor83]

same as cramya...it is E.
Cramya...pls reply my PM..I m waiting.

9/12=x/3
x = 9/4

[parallel_chase]

I totally agree with cramya's solution as posted above. Just want to elucidate the fact:

after drawing the figure, we get two similar triangles, with the same base and having 1 angle of 90 degrees each, one with base 12 and another with base 3.
The triangle with base 12 has a height 9.

Therefore,

12/9 = 3/x

x = 9/4.

Hence E.

[Brent@GMATPrepNow]

The answer isn't E, but you are correct about the similar triangles.

[parallel_chase]

Hey Brent is it 9/5?

I hope this is correct.

[vivek.kapoor83]

is the ans C...i solved it by trignometry.
after drawing fig and solving by Tangent x = p/b =9/15
and then using similar trinangle concept and using the vaule of tan x
i got it to C...is it the rite choice.9/5

[Brent@GMATPrepNow]

Nice work.

There are two similar triangles:

Triangle 1: Height = 9 (lamp post) and base = 15 (12 meters PLUS 3 meter shadow)

Triangle 2: Height = x (Joe) and base = 3 (shadow).

We get 9/15 = x/3 (or 9/x = 15/3 . . . etc)

Solve for x to get 9/5 (C)

[vivek.kapoor83]

was trigonometry d rite approach here..coz we use to solve it in school classes..similar ques i rem..

[mental]

tried to give the solution

Its same as Brent's.