Question

A vertical meter stick casts a shadow 40 cm long at the same time a flagpole casts a shadow 10 feet long. How tall is the flagpole?

Answer 1

The first step we need to take is to convert the size of the meter stick to centimeters. This is done below:

$1m=100\operatorname{cm}$

Now that both the height and the shadow are on the same unit, we can create a proportion to determine the height of the flag. Which is done below:

$\frac{100\text{ cm}}{40\text{ cm}}=\frac{x\text{ ft}}{10\text{ ft}}$

We can eliminate the units, then cross multiply to determine x.

$\begin{gathered} \frac{100}{40}=\frac{x}{10} \\ 40\cdot x=100\cdot10 \\ 40\cdot x=1000 \\ x=\frac{1000}{40}=25 \end{gathered}$

The flag has a height of 25 ft.