Question

A telephone pole 13 1/3 feet tall casts a shadow of 16 feet when a person casts a shadow of 6 feet. How tall is the person?
4 1/3ft
5ft
5 1/3ft

Answer 1

This is a proportion problem. So let's two proportions equal to each other since we know the ratio between height and shadow are the same.

13.333/16 = x/6

*cross multiply
79.999 = 16x

*now solve for x by dividing 16 both sides of the equation

79.999/16 = (16/16)x

x = 4.999 or 5 ft

Answer 2

oh that makes sens now thank you so much for helping me and showing me how to do it

Answer 3

Never "cross-multiply". That doesn't mean anything.

You had this: \(\dfrac{13.333}{16} = \dfrac{x}{6}\)

If you "cross-multiply", which doesn't mean anything, you have done two operations: 1) Multiple both sides by 6 and 3) Multiply both sides by 16. This leaves:

\(80 = 16x\)

The solution, after "cross-multiplying", is obtained by dividing by 16. WAIT!! Didn't we just Multiply by 16? Well, THAT was a waste of time.

Just multiply. That's all.

You had this: \(\dfrac{13.333}{16} = \dfrac{x}{6}\)

Multiply by 6. \(\dfrac{13.333}{16}\cdot 6 = x = 5\) -- Done.

Answer 4

oh that seems way easier then the other way thank you so much

Answer 5

Learn the basic operations. "cross-multiply" is NOT one of them.