8. Ratios and Proportions
How do you use the ratio box?
1. Fill in the ratio 2. Fill in whatever actual #'s are provided by the problem 3. Add the two ratio to get to the total 4. Find the multiplier using the #'s in the 1st row and the numbers in the last row 5. Fill in the multiplier for the entire row 6. Multiply to find the actual numbers
What is a fraction?
A fraction expresses a part to whole relationship
What is a proportion?
A proportion is an equation relating to either two fractions or two ratios.
How do you solve a proportion question?
Set up the proportion with the known relationship on the left and the unknown relationship on the right.
How does the GMAT write ratios?
The GMAT writes ratios the same way they write fractions.
What are proportions used for?
To scale ratios up or down
How do you draw a ratio box?
Use the ratio, multipler, and actual numbers as the three rows Use the question stem to fill in the column headers Fill in the information provided in the problem Use this information to calculate the missing values
What equation can be used to set up proportions?
X1/y1 = x2/y2
Should you label your proportions?
Yes, it is a good idea to label proportions to make sure all the numbers line up in the correct place
What do proportions compare?
You use a proportion when the unknown relationship compares the same items to the known relationship
What is a ratio?
A ratio expresses a part to part relationship
What are the steps when solving for a proportion?
First write down the ratio given, next write down what else is known and solve for the unknown.
