SAT Practice Problem
Solution:
You have been taught to write “the ratio of a to b is 3 to 2” in two main ways:
- a : b = 3 : 2
- a/b = 3/2
On the SAT, the most beneficial way to write that ratio is a : b = 3x : 2x.
By including the x, you make it easy to determine all possible combinations of a and b that provide that specific ratio.
Looking at this question in particular:
You are told that the ratio of raisins to dates is 7 to 3.
r : d = 7x : 3x
This means you have 7x pounds of raisins and 3x pounds of dates. You can write an equation to figure out how many total pounds of raisins and dates you have:
raisins + dates = total
Substitute 7x for raisins and 3x for dates: |
7x + 3x = total |
Substitute 7 pounds for the total: |
7x + 3x = 7 |
Combine terms: |
10x = 7 |
Divide by 10: |
x = 7/10 pounds = .7 pounds |
The total weight of raisins is equal to 7x pounds. |
Substitute 0.7 for x |
7(0.7) = 4.9 pounds |
Choice E!
Provided by The Learning Edge
