SAT Math : Arithmetic

Study concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #3 : How To Find A Ratio

The ratio of  to  is  to , while the ratio of  to  is  to .

What is the ratio of  to ?

Possible Answers:

Correct answer:

Explanation:

Since the ratios are fixed, regardless of the actual values of , , or , we can let  and

In order to convert to a form where we can relate  to , we must set the coefficient of  of each ratio equal such that the ratio can be transferred. This is done most easily by finding a common multiple of  and  (the ratio of  to  and , respectively) which is

Thus, we now have  and .

Setting the  values equal, we get , or a ratio of 

Example Question #21 : How To Find A Ratio

The exchange rate in some prehistoric village was  jagged rocks for every  smooth pebbles.  Also, one shiny rock could be traded for  smooth pebbles.  If Joaquin had  Jagged rocks, what is the maximum number of shiny rocks he could trade for?

Possible Answers:

Correct answer:

Explanation:

We can use dimensional analysis to solve this problem.  We will create ratios from the conversions given.

Since Joaquin cannot trade for part of a shiny rock, the most he can get is 3 shiny rocks.

Example Question #501 : Arithmetic

In a flower bed, Joaquin plants  Begonias for every  Zinnias, and  Marigolds for every  Begonias.  What is the ration of Marigolds to Zinnias planted in the flower bed?

Possible Answers:

Correct answer:

Explanation:

First, we should write a fraction for each ratio given:

 

Next, we will multiply these fractions by each other in such a way that will leave us with a fraction that has only Z and M, since we want  a ration of these two flowers only.

So the final answer is 35:6

Example Question #23 : How To Find A Ratio

Solve for

Possible Answers:

Correct answer:

Explanation:

To solve for the missing value in this ratio problem, it is a two step process.

First cross-multiply:





From here, to isolate x take the opposite operation. In other words divide each side by two.

Example Question #1 : Fractions

A lawn can be mowed by  people in  hours. If  people take the day off and do not help mow the grass, how many hours will it take to mow the lawn?

Possible Answers:

Correct answer:

Explanation:

The number of hours required to mow the lawn remains constant and can be found by taking the original  workers times the  hours they worked, totaling  hours. We then split the total required hours between the  works that remain, and each of them have to work  and  hours:  .

Example Question #1 : How To Find Rate

A family is on a road trip from Cleveland to Virginia Beach, totaling 600 miles. If the first half of the trip is completed in 6.5 hours and the second half of the trip is completed in 5.5 hours, what is the average speed in miles per hour of the whole trip?

Possible Answers:

60 mph

50 mph

45 mph

55 mph

65 mph

Correct answer:

50 mph

Explanation:

Take the total distance travelled (600 miles) and divide it by the total time travelled (6.5 hrs + 5.5 hrs = 12 hours) = 50 miles/hour 

Example Question #2 : How To Find Rate

Two electric cars begin moving on circular tracks at exactly 1:00pm. If the first car takes 30 minutes to complete a loop and the second car takes 40 minutes, what is the next time they will both be at the starting point?

Possible Answers:

1:35 p.m.

4:00 p.m.

2:40 p.m.

3:30 p.m.

3:00 p.m.

Correct answer:

3:00 p.m.

Explanation:

Call the cars “Car A” and “Car B”.

The least common multiple for the travel time of Car A and Car B is 120. We get the LCM by factoring. Car A’s travel time gives us 3 * 2 * 5; Car B’s time gives us 2 * 2 * 2 * 5.  The smallest number that accommodates all factors of both travel times is 2 * 2 * 2 * 3 * 5, or 120. There are 60 minutes in an hour, so 120 minutes equals two hours. Two hours after 1:00pm is 3:00pm.

Example Question #2 : How To Find Rate

If Jon is driving his car at ten feet per second, how many feet does he travel in 30 minutes?

Possible Answers:

5,800

18,000

12,000

600

1800

Correct answer:

18,000

Explanation:

If Jon is driving at 10 feet per second he covers 10 * 60 feet in one minute (600 ft/min). In order to determine how far he travels in thirty minutes we must multiply 10 * 60 * 30 feet in 30 minutes.

Example Question #2 : How To Find Rate

An arrow is launched at 10 meters per second. If the arrow flies at a constant velocity for an hour, how far has the arrow gone?

Possible Answers:

100 meters

3600 meters

36,000 meters

600 meters

Correct answer:

36,000 meters

Explanation:

There are 60 seconds in a minute and 60 minutes in an hour, therefore 3600 seconds in an hour. The arrow will travel 3600x10= 36,000 meters in an hour.

Example Question #2 : How To Find Rate

If Jack ran at an average rate of 7 miles per hour for a 21 mile course, and Sam ran half as fast for the same distance, how much longer did it take for Sam to run the course than Jack?

Possible Answers:

1 hour

4 hours

2.5 hours

3 hours

2 hours

Correct answer:

3 hours

Explanation:

Using the rate formula:  Distance = Rate x Time,

Since Jack’s speed was 7 mph, Jack completed the course in 3 hours

21 = 7 x t

t = 3

Sam’s speed was half of Jack’s speed: 7/2 = 3.5

21 = 3.5 x t

t = 6

Therefore it took Sam 3 hours longer to run the course.

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