To review these concepts, go to Algebra Ratios and Proportions Study Guide.
Algebra Ratios and Proportions Practice Questions
Practice 1
Answer the following questions.
 The ratio of red cars to blue cars in a parking lot is 1:6. If there are 36 blue cars, how many red cars are in the lot?
 The ratio of lemon candies to strawberry candies in a dish is 3:8. If there are 9 lemon candies, how many strawberry candies are in the dish?
 If the ratio of bass to trout in a pond is 4:5, and there are 135 trout, how many bass are in the pond?
 If the ratio of basketball players to football players at Roward Middle School is 2:7, and there are 54 total basketball and football players, how many basketball players are there?
 The ratio of adults to children at a movie is 3:4. If there are 196 people at the movie, how many of them are children?
Practice 2
Answer the following questions
 The ratio of black pens to blue pens in a box is 7:4. If there are 9 more black pens than blue pens, how many blue pens are there?
 The ratio of fiction books to nonfiction books on a shelf is 6:5. If there are 4 more fiction books than nonfiction books, how many fiction books are there?
 The ratio of parents to students on a school trip is 2:9. If the number of students was 6 more than 4 times the number of parents, how many parents went on the trip?
Solutions
Practice 1

Write the ratio of red cars to blue cars as a fraction. 1:6 = .
The number of red cars is unknown, so represent that number with x.
The ratio of actual red cars to actual blue cars is x:36, or .
Set these ratios equal to each other, cross multiply, and solve for x:
6x = 36
x = 6
There are 6 red cars in the parking lot.

Write the ratio of lemon candies to strawberry candies as a fraction. 3:8 = .
The number of strawberry candies is unknown, so represent that number with x. The ratio of actual lemon candies to actual strawberry candies is 9:x, or .
Set these ratios equal to each other, cross multiply, and solve for x:
3x = 72
x = 24
There are 24 strawberry candies in the dish.

Write the ratio of bass to trout as a fraction. 4:5 = .
The number of bass is unknown, so represent that number with x. The ratio of actual bass to actual trout is x:135, or .
Set these ratios equal to each other, cross multiply, and solve for x:
5x = 540
x = 108
There are 108 bass in the pond.

The ratio of basketball players to football players is 2:7, which means that the ratio of basketball players to total players is 2:(2 + 7) = 2:9. Write this ratio as a fraction:
The number of basketball players is unknown, so represent that number with x. The ratio of actual basketball players to actual total players is x:54, or .
Set these ratios equal to each other, cross multiply, and solve for x:
9x = 108
x = 12
There are 12 basketball players at Roward Middle School.

The ratio of adults to children is 3:4, which means that the ratio of children to total people is 4:(3 + 4) = 4:7. Write this ratio as a fraction. 4:7 = .
The number of children is unknown, so represent that number with x. The ratio of actual children to actual people is x:196, or .
Set these ratios equal to each other, cross multiply, and solve for x:
7x = 784
x = 112
There are 112 children at the movie.
Practice 2

The number of blue pens is unknown, so represent that number with x.
There are 9 more black pens than blue pens, which means that the number of black pens is equal to x + 9. The ratio of black pens to blue pens is 7:4, or .
The ratio of actual black pens to actual blue pens is (x + 9):x, or .
These ratios are equal. Write a proportion and solve for x:
7x = 4x + 36
3x = 36
x = 12
There are 12 blue pens in the box.

The number of fiction books is unknown, so represent that number with x.
There are 4 more fiction books than nonfiction books, which means that the number of nonfiction books is equal to x. – 4. The ratio of fiction books to nonfiction books is 6:5, or . The ratio of actual fiction books to actual nonfiction books is x:(x – 4), or .
These ratios are equal. Write a proportion and solve for x:
5x = 6x –24
–x = –24
x = 24
There are 24 fiction books on the shelf.

The number of parents is unknown, so represent that number with x.
The number of students is 6 more than 4 times the number of parents, which means that the number of students is equal to 4x + 6. The ratio of parents to students is 2:9, or . The ratio of actual parents to actual students is x:(4x + 6), or .
These ratios are equal. Write a proportion and solve for x:
9x = 8x + 12
x = 12
Therefore, 12 parents went on the trip.
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