Question

Write a problem that could be modeled with y=200(0.9).

Answer 1

First, I need to decide what equation this is like.

I believe this is y=mx.

We know that x is typically the input, and m is the constant function.

Y is the output.

So the original function may have been y=200x.

The only difference is now we've been given something to apply to the equation, in place of x.

2. Imagine a cloning machine. Whatever you put in, you get a copy of, and the original thing you put in. Its function would be y=2x. Let's pretend we decided to put three things in; 3 would go where x is.

Y would be the result of 3 copies and their originals, or 2(3).

(6=2(3))

Now, when someone else decides to use the cloning machine, they may put any number in, but the only properties that will change are y and x, not m.

The function will remain y = 2x. Any number could go in place of x, and multiplying x by 2 will give you the y. As long as you have a different value for x, the y will never be the same.

3. So now we have an understanding of what it means, we see that we have been given an x value to insert; an input.

A more practical example could be someting with money. This won't be entirely realistic, because we are dealing with a fraction of a number and another large number.

4. I decided to go with flour. I wanted the 200 to represent pennies, or cents. Before I landed on this, I looked up the cost of flour per pound. I found that the average is .43 dollars, which isn't terribly close to two dollars. But maybe the flour is high quality, so we can stick with that.

5. Seeing that this equation, y=200x, means we are charging 200 cents, or two dollars, we can write a problem from here.

Sylvia is in charge of selling home-harvested flour from an organic farm. She charges two dollars per pound of flower. Today, her next-door neighbors hope to buy a ninth of pound of flour, and they insist on paying with pennies. How many pennies do they need to pay for their order?

Let me know if this helped, or if you have any questions!