Question

You are 5 feet tall and cast an 8-foot shadow. A lamppost nearby casts a shadow that is 20 feet. Which equation can you use to solve for the height (h) of the lamppost?

Answer 1

Height of n1 divided by shadow of n1 = height of n2 divided by shadow of n2. 5/8 = n/20 , or to put it in other words, 5 divided by 8, then multiplied bu 20, which is 12.5ft.

Answer 2

The equation to solve is
`h=(20*5)/(8)` and as a result it is obtained that the lamppost height is 12.5 feet.

Explanation:

The rule of three or is a way of solving problems of proportionality between three known values and an unknown value, establishing a relationship of proportionality between all of them. That is, what is intended with it is to find the fourth term of a proportion knowing the other three. Remember that proportionality is a constant relationship or ratio between different magnitudes.

If the relationship between the magnitudes is direct, that is, when one magnitude increases, so does the other, the direct rule of three must be applied. To solve a direct rule of three, the following formula must be followed:

The direct rule of three is the rule applied in this case as follows: if you are 5 feet tall and cast a shadow of 8 feet, how much will be the height (h) of the lamppost if you cast a shadow of 20 feet?

`h=(20*5)/(8)`

h=12.5 feet

So, the equation to solve is
`h=(20*5)/(8)` and as a result it is obtained that the lamppost height is 12.5 feet.