# SSAT Middle Level Math : How to find a proportion

## Example Questions

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

Give the value of  that makes this proportion statement correct:

Explanation:

Cross-multiply, then solve for :

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

Give the value of  that makes this proportion statement correct:

Explanation:

Cross-multiply, then solve for :

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

Give the value of  that makes this proportion statement correct:

Explanation:

Multiply both sides by 80 and solve for :

### Example Question #122 : Ratio And Proportion

Give the value of  that makes this proportion statement correct:

Explanation:

Multiply both sides by 75 and solve for :

### Example Question #5 : How To Find A Proportion

Read this problem, but do not solve it.

4 out of every 5 dentists surveyed recommend Triton sugarless gum to patients who chew gum. If 2,100 dentists were surveyed, how many dentists recommended Triton?

If we let  be the number of dentists who recommended Triton, what proportion statement could be used to solve this problem?

Explanation:

The ratios that are set equal to each other in a proportion statement must compare the same quantities in the same order.

In each ratio, we can put number of dentists who recommended Triton in the numerator, and number of dentists who were surveyed in the denominator.

One ratio is 4 dentists recommending Triton to 5 dentists surveyed (the general ratio): this is .

The other ratio is  dentists recommending Triton to 2,100 dentists surveyed (the actual number); this is .

The proportion statement sets these equal:

which is the correct choice.

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

If Jason eats one-third of half a dozen donuts, how many donuts has he eaten?

donuts

donuts

donuts

donuts

donuts

donuts

Explanation:

Half a dozen donuts is equal to 6 donuts, given that there are 12 items per dozen.

One-third of 6 is 2. Therefore, 2 donuts is the correct answer.

### Example Question #123 : Ratio And Proportion

Kenny is having a party, and he is experimenting with different mixtures of soda to come up with something original. He particularly likes a mixture of four ounces of lemon lime soda and three ounces of cream soda. He has two and a half liters of lemon lime soda and wants to use it all; how much cream soda does he need?

None of the other responses gives the correct answer.

Explanation:

The ratio of ounces of lemon lime soda to ounces of cream soda in the initial mixture can be expressed as . This ratio must remain the same for the mixture Ken will make for the party. Let  be the number of liters of cream soda. Then the ratio is . Set the two ratios equal to each other and solve for :

Set the cross-products equal to each other:

Ken will use   liters of cream soda in the final mixture.

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

What is the value of  in the proportion?

Explanation:

Simplify  by dividing both the numerator and denominator by 8 so that it simplifies to .  Now it should be obvious that  in order for both sides of the equation to be equal.

### Example Question #4 : How To Find A Proportion

For every $3 I earn at work, I donate$1 to charity. How much money will I donate if I make \$27.00/week.

Explanation:

To find the amount of the donation, divide 27 by 3.

### Example Question #10 : How To Find A Proportion

A Spanish class has  seniors and  juniors. What proportion of the class is juniors?