# Common Core: 7th Grade Math : Decide if Two Quantiies are in a Proportional Relationship: CCSS.Math.Content.7.RP.A.2a

## Example Questions

### Example Question #3 : Proportion / Ratio / Rate

In a class of  students, the ratio of freshmen to sophomores to juniors is . How many juniors are in the class?

Explanation:

Let  be the number of freshmen,  be the number of sophomores, and  be the number of juniors.

Now, since we have  students,

Since we want to find the number of juniors, we need to find the value of .

### Example Question #4 : Proportion / Ratio / Rate

In a zoo with  animals, the ratio of mammals to reptiles to birds is . How many birds does the zoo have?

Explanation:

Let  be the number of mammals, be the number of reptiles, and  be the number of birds.

Since the zoo has  animals,

Because we want the number of birds, we need to find the value of .

### Example Question #1 : Proportion / Ratio / Rate

In a high school of  students, the ratio of freshmen to sophomores to juniors to seniors is . How many juniors does this high school have?

Explanation:

Let  be the number of freshmen,  be the number of sophomores,  be the number of juniors, and  be the number of seniors.

Because the high school has  students,

Since we want to find out how many juniors there are, we need the value of .

### Example Question #1 : Rational Numbers

In a high school, the ratio of freshmen to seniors is . If there are  seniors, how many freshmen are there?

Explanation:

Set up the following proportion, with  being the number of freshmen.

Now, cross-multiply and solve for .

### Example Question #1 : Proportion / Ratio / Rate

On a beach, the ratio of crabs to seagulls is . If there are  crabs and seagulls on the beach, how many crabs are there?

Explanation:

Let  be the number of crabs and  be the number of seagulls.

Since there are  crabs and seagulls on the beach,

Because the question asks for the number of crabs, we need to find the value of .

### Example Question #1 : Proportion / Ratio / Rate

There are  boys and  girls at a playground. What is the ratio of boys to girls?

Explanation:

Write the numbers of boys and girls as a fraction, then simplify.

can also be written as

### Example Question #1 : How To Find A Ratio

At a high school, there are  freshmen,  sophomores,  juniors, and  seniors. What is the ratio of seniors to freshmen?

to

to

to

to

to

Explanation:

Write the number of seniors and numbers of freshmen as a fraction:

That fraction is equivalent to .

### Example Question #10 : Proportion / Ratio / Rate

The angles in a triangle are in the ratio . What is the angle measurement of the largest angle?

Explanation:

Let  be the values of the angles.

Since all the angles in a triangle need to add up to ,

Because we want the value of the largest angle, we need to find the value of .

### Example Question #1 : Decide If Two Quantiies Are In A Proportional Relationship: Ccss.Math.Content.7.Rp.A.2a

John and Michela are business partners who agreed to split profits at a ratio of 2:3, with Michela taking the larger share. If their business made  in the first year, how much money did Michela make?

Explanation:

Let  be the amount John takes home and  be the amount Michela takes home.

We want to know how much Michela made so we need to find the value of .

### Example Question #2 : Decide If Two Quantiies Are In A Proportional Relationship: Ccss.Math.Content.7.Rp.A.2a

The angles in a triangle have a ratio of . What is the measurement of the smallest angle?