SAT Math : Proportion / Ratio / Rate

Study concepts, example questions & explanations for SAT Math

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Example Questions

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Example Question #81 : Proportion / Ratio / Rate

A recipe calls for a ratio of  for wheat, barley, and flour. If we have 12 pounds of barley, how much wheat do we need to use all of it?

Possible Answers:

Correct answer:

Explanation:

We can set up a ratio of  and then solve for

Example Question #11 : How To Find Proportion

To ship a package, the postal service charges  for the first 150 grams and  for each additional 50 grams or part thereof. What is one possible weight in grams for a package that costs  to ship?

Possible Answers:

Correct answer:

Explanation:

The weight will be 150 grams + (1.15 – 0.55)/0.05 * 50g.

You need to subtract first 150 grams cost from the total cost and divide by the price per unit to determine how many units. Next, multiply units by weight per unit and add to the original first 150 grams.

 150 + 600 = 750 grams

This is the maximum weight that can be sent at that price; the minimum weight that could be charged this price would be 701 grams. Hence a package weighing 750 grams will be charged $1.15.

Example Question #17 : How To Find Proportion

Six is to thirteen-and-a-half as seventeen is to what?

Possible Answers:

None of the other answers are correct.

Correct answer:

Explanation:

Let us express this as an algebraic expression:

\frac{6}{13.5}=\frac{17}{x}

We can cross multiply:

6x=13.5\times 17

6x=229.5

x=\frac{229.5}{6}=38.25

Example Question #11 : How To Find Proportion

Solve the proportion:  

Possible Answers:

Correct answer:

Explanation:

Cross multiply the proportion and simplify.

Example Question #12 : How To Find Proportion

Toilet  used  gallons of water in the last hour and uses  gallon of water per flush.  If Toilet  was flushed the same amount, but uses  gallons per flush, how much water did Toilet  use?

Possible Answers:

 gallons

 gallons

 gallons

 gallons

 gallons

Correct answer:

 gallons

Explanation:

First you must figure out the proportion . You then cross multiple to get  meaning that Toilet  uses  gallons.

Example Question #20 : How To Find Proportion

In a ceratain class,  of the students are boys and  of the boys are freshman.  If all of the freshmen boys failed the first test, which could be the total number of students in the class?

Possible Answers:

Correct answer:

Explanation:

In order the split the boys equally in half to have them be freshmen, a third of the class must be an even number.  The only choice that when cut in thirds can then be split in half is .   and .

Example Question #83 : Proportion / Ratio / Rate

Out of 85 students in a certain class, 42 own a laptop and 54 own an mp3 player. If 5 students don't own either, what fraction of the students own both a laptop and an mp3 player?

Possible Answers:

7/40

19/80

16/85

1/10

1/8

Correct answer:

16/85

Explanation:

Once you subtract the 5 students that don't own either, there are 80 students left.

There's 96 total students when you add the number that own an mp3 and the number that own a laptop, meaning 16 own both.

Recall that the fraction will be number of students who have both laptop and mp3 divided by the total students in the class.

Example Question #81 : Proportion / Ratio / Rate

For every 5 glasses of lemonade, Bud earns $2. How many glasses must he sell to earn $24? 

Possible Answers:

Correct answer:

Explanation:

We can set up a simple proportion to solve this. For every 5 glasses, Bud gets $2. For every x glasses, he earns $24. 

 

Example Question #22 : How To Find Proportion

Mindi can take down seven museum displays every half hour. How many displays can she take down completely in an hour and fifteen minutes?

Possible Answers:

Correct answer:

Explanation:

Let's set up a proportion to solve this problem, like so:

We can cross-multiply and solve for the unknown. We can ignore our units for now as the answer's units will result in displays as the unit. 

This means that Mindi can take down  displays in the given time. However, the question asks for the number of displays she can take down completely in the given time. This means that our answer is rounded down to 

Example Question #23 : How To Find Proportion

A rabbit runs at a speed of  miles per hour. How long does it take for it to run  miles? 

Possible Answers:

Correct answer:

Explanation:

Let's set up a proportion to help solve this problem. We can say:

Now, we can cross-multiply and solve for the unknown. Don't worry about units for now. They will cancel out and leave us with hours as the units for our answer. 

Therefore, our answer is  hours. 

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