how do you get the scale factor? how do you get the ratio?

Question

in english please, i have these definitions in my book but i cant understand them!
thnx!

umm...i said in english
i know, i know, im a ****** up turkey when it comes to math

Answer 1

It would probably help if you posted the definitions.

In general, though the "scale factor" is usually the the ratio of the size of a copy of an object to the actual size of the object.

As an example, if you look at a map, they usually say somewhere something like "1 inch = 10 miles". So if you are trying to find the distance between two cities, and they are 3.5 inches apart on the map, the cities are 3.5 inches x 10 miles/inch = 35 miles apart.

Since the scale factor IS a ratio, I don't understand the second question.

Answer 2

A ratio is used to compare 2 numbers.

For example, 20 children to 4 buses.

In math, we write it this way:

20 to 4

OR

20/4

OR

20 : 4

This means, in our case, 20 children compared to 4 buses.

Ratio = a comparison of two numbers.

A scale factor is a number which scales some quantity.

For example, in the equation y = C times x, C is the scale factor that when multiplied by x (whatever x is) will produce different values for y. The scale factor remains the same.

I guess the best way is with a sample question.

Solve for y when x = 2, x = 4 and the scale factor is 2.

y = Cx

y = 2(2)

y = 4.

y = Cx

y = 2(4)

y = 8

We got two different answers for y using the same scale factor of 2 BUT at the same time, using different values for x.

See my point?

Guido

Answer 3

Ratio

The result of dividing one number or expression by another. Sometimes a ratio is written as a proportion, such as 3:2 (three to two). More often, though, ratios are simplified according to the standard rules for simplifying fractions or rational expressions.
http://www.mathwords.com/r/ratio.htm

Scale Factor

The ratio of any two corresponding lengths in two similar geometric figures. Note: The ratio of areas of two similar figures is the square of the scale factor. The ratio of volumes of two similar figures is the cube of the scale factor.
http://www.mathwords.com/s/scale_factor.htm