Imagine building something without making any kinds of plans whatsoever.
You could do it, but it probably wouldn't turn out quite the way you envisioned.
Before constructing something as immense as the Three Gorges Dam,
architects and engineers make all kinds of very detailed plans,
and use many problem-solving approaches.
An especially important one is making a model.
They might have made drawings of the dam first,
but to apply the measurements, ratios and proportions they put on paper
to something concrete, something real that has three dimensions,
a model is necessary.
Engineers and architects developed a computer model of the Three Gorges Dam.
From that, they plan to build a physical model
so that 1 inch of the model represents 100 feet of the real dam.
Let's calculate the size of the model they needed to make,
based on the proposed size and scale of the dam.
The architects know the dam must be 575 feet tall,
so we must convert that to model-inches.
Since each model-inch is equal to 100 feet,
then to get model-inches for 575 feet, we can divide by equal quantities.
That's one model-inch on the left and 100 feet on the right.
We divide 575 by 100 to figure out that the scale model will be 5.75 inches tall.
The actual dam must stretch about 7,600 feet across the river, so based on its scale,
the model will be 76 inches long, nearly 6 1/3 feet.
The actual dam will be enormous; more than a mile long.
So studying a model helps us understand how huge
and gives the engineers the ability to envision potential features,
advantages, disadvantages or problems of this massive structure.