SOLUTION: A light post casts a shadow that is 15 ft. long. Sarah is 5 ft. tall and is standing 4 ft. from the light post. How tall is the light post?

Algebra.Com
Question 1206337: A light post casts a shadow that is 15 ft. long. Sarah is 5 ft. tall and is standing 4 ft. from
the light post. How tall is the light post?
Found 3 solutions by math_tutor2020, ikleyn, MathTherapy:
Answer by math_tutor2020(3817)   (Show Source): You can put this solution on YOUR website!


h = height of the lamp post
h/19 = 5/15 due to similar triangles
15h = 19*5 cross multiply
h = 19*5/15
h = 6.3333 feet approximately

Answer by ikleyn(52781)   (Show Source): You can put this solution on YOUR website!
.

Wording is very strange, inadequate and confusing in this post.

It is not a light post casts a shadow of 15 ft.

In opposite,    casts a shadow of 15 ft long.


This post is not a Math problem - it is a soup of words, instead.

To be a Math problem, it should be re-written from the scratch.



Answer by MathTherapy(10552)   (Show Source): You can put this solution on YOUR website!
A light post casts a shadow that is 15 ft. long. Sarah is 5 ft. tall and is standing 4 ft. from 
the light post. How tall is the light post?

In most cases, the TIP of the person's shadow touches the TIP of the object's (light post, in this
case) shadow
As such, let's say the height of the light post is H
With the light post casting a 15-ft shadow, and considering that Sarah is standing 4 ft from it -
on the SAME side as its shadow - then Sarah's shadow is 11 (15 - 4) ft long
We then get the following PROPORTION: 
                                                                    
                                                                    11H = 15(5) ------ Cross-multiplying
                                                                    11H = 75
                                        Light post's height, or

RELATED QUESTIONS

A 4-ft fence post casts a shadow 9-ft long at the same time a tree casts a 52-ft shadow.... (answered by solver91311)
If a 5 ft tall tent casts a 4 ft long shadow, then how long is the shadow that a 15 ft... (answered by josgarithmetic)
A person standing 40 ft away from a street light that is 25 ft tall. How tall is he if... (answered by Boreal)
how tall is a tree that cast a 25-ft.shadow at the same time a 9-ft light pole casts a... (answered by CubeyThePenguin)
Llong is 5 ft tall and is sanding in the light of a 15-ft lamppost. Her shadow is 4 ft... (answered by richwmiller)
Grace is 4 ft. tall and standing in the light of a 20 ft. tall lamppost. her shadow is 8... (answered by scott8148)
A light post whose base is 30 ft from a 4 story building has fallen over. If the tip of... (answered by JulietG)
a 5-ft tall girl casts a shadow 8 ft. long. she is standing next to a tree that casts a... (answered by checkley77)
A 10 ft tall tent standing next to a baby elephant casts a 20 ft shadow. If the baby... (answered by josgarithmetic)