Jesse writes:I was wondering If u could let me know if I got these two questions correct I’m taking my ged next week & I want to feel comfortable with this math.

On a map 1/3 in=15 miles find the distance between two towns on a map that equals 3 2/3 in. How many miles r between the two? my answer was 75 miles am I correct?Next QuestionThe scale on a map indicates that 1/2 inch represents an actual distance of 120 miles, how far apart will two towns be if the actual distance between them is 180 miles my answer was 2 inches am I correct? if not could u explain how to set up these type of problems? thank you, Jesse.

Jesse,

Hey! Congrats on your GED test comin’ up. Y’know what these questions are? Ratios. I got a ratio post on my blog at: http://www.passged.com/student_blogs/curtis/2007/12/24/rice-ratios-gotta-love-that-ged-math/

There’ll prolly be a ratio question on the GED test. Here’s how it works. Take the first question. You got 1/3 inch, that equals 15 miles. Picture it in your head. Say this line is 1/3 inch: |—| It be 15 miles.

So, you got to find out how many miles in 3-2/3 inch. Well, first you gotta find out, how many 1/3-inches are in 3-2/3 inch. Get it?

Three 1/3-inch lengths are in 1 inch, like this:

|—|—|—|

So, in 3-2/3 inches, there’s 11 1/3-inch lengths:

|—|—|—|

|—|—|—|

|—|—|—|

|—|—|

Each 1/3-inch is 15 miles, right? So, we got 11 lengths of 15 miles… that’s 15 times 11, and that’s 165 miles! There ya go. Always makes it easier to understand to picture it in your head.

If you want to do it mathematically, what I did was set up a ratio:

1/3:15

3-2/3:x

Divide 3-2/3 by 1/3… then multiply 15 by the answer to get x.

Here’s the other one.

1/2 inch = 120 miles

x = 180 miles

Same deal here, right? You got a ratio.

1/2 inch:120 miles

x:180 miles

The relationship between 120 and 180 got to be the same as between 1/2 and the answer. So, what’s the relationship between 120 and 180? If you divide 180 by 120, 180/120 = 18/12 = 9/6 = 3/2 = 1-1/2

So, 180 is 1-1/2 times 120. Then x got to be 1-1/2 times 1/2. That’s 3/4. If it’s easier, you can do 1.5 x .5 = .75 …same thing. So, the answer’s 3/4 inch. Get it?

Hope this helps!

Curtis

For more information about the GED test and GED test preparation, visit The GED Academy at http://www.passged.com.