SAT Math : Algebra

Study concepts, example questions & explanations for SAT Math

varsity tutors app store varsity tutors android store varsity tutors ibooks store

Example Questions

Example Question #4 : How To Find The Solution For A System Of Equations

If 8x – 9 is 10 less than 5, what is the value of 4x?

Possible Answers:

2

1/2

4

1/4

1

Correct answer:

2

Explanation:

The first thing to do is to write an algebrai equation for the problem:

8x – 9 = 5 – 10

8x – 9 = –5

8x = 4  

x = 1/2

Thus, 4 * x = 2

Example Question #5 : How To Find The Solution For A System Of Equations

4x - 5y = 12

6y - 3x = -6

Quantity A: x + y

Quantity B: 6

Possible Answers:

The two quantities are equal

The relationship cannot be determined from the information given

Quantity B is greater

Quantity A is greater

Correct answer:

The two quantities are equal

Explanation:

Add the two equations:

4x - 5y = 12 plus

6y - 3x = -6:

4x - 5y + (6y - 3x) = 12 + (-6)

4x - 3x + 6y - 5y = 12 - 6

x + y = 6

Example Question #6 : How To Find The Solution For A System Of Equations

  1. A charity organization is signing up volunteers to prepare for a fundraiser.  Each volunteer can either help setup tables or auction galleries.  A volunteer can setup 6 tables per hour or 2 auction galleries per hour.  There are 180 tables to be setup as well as 12 auction galleries.  If the volunteers will have 3 hours to prepare, how many volunteers must be signed up?

 

Possible Answers:
30
8
10
12
15
Correct answer: 12
Explanation:

Find out how much a volunteer can produce in 3 hours.

6 tables/hour * 3 hours = 18 tables/hour

180 table need to be setup.  If one volunteer can setup 18 in 3 hours, then 10 volunteers will take care of the 180 tables.

2 auction galleries/hour * 3 hours = 6 galleries/hour

2 volunteers will be able to complete 12 auction galleries

10 + 2 = 12 volunteers

Example Question #5 : How To Find The Solution For A System Of Equations

If  x + 12 = 28, what is the value of (3x + 2) * (–x + 10)?

Possible Answers:

1300

–300

–1300

450

–180

Correct answer:

–300

Explanation:

Solve for x, then plug into the formula to find the value.  x = 28 – 12 = 16

(3 * 16 + 2) * (–16 +10) = –300

Example Question #7 : How To Find The Solution For A System Of Equations

Joey has $1.50. If he only has quarters and nickels and he has 14 coins total, how many nickels does he have?

Possible Answers:

8

6

5

3

10

Correct answer:

10

Explanation:

Setting x and the number of quarters he has and y as the numbver of nickels. x + y = 14 (total coins), 0.25x + 0.05y = 1.50 (total amount). Substituting x = 14 – y from the first equation into the second, we get y = 10. Therefore Joey has 10 nickels.

Example Question #1 : Systems Of Equations

A soccer player kicks a ball at 8m/s. A player runs to receive it as soon as the ball as kicked at a speed of 4m/s. If the receiving player starts 12m ahead of the ball, how far does he travel before he gets the ball?

Possible Answers:

6 m

3 m

9m

15m

12m

Correct answer:

12m

Explanation:

Setting t as the time elapsed we need to find when 8t = 12 + 4t (this is the distance traveled by the ball compared to the distance traveled by the player+difference from origin). Solving for t we get a travel time of 3 seconds. If the player runs for 3 seconds at 4m/s, the player travels 12m before receiving the ball.

Example Question #221 : Algebra

Let f(x) = 2x2 – 3x + 1, and let g(x) = 13 – x. What is the distance between the points of intersection of f(x) and g(x)?

 

Possible Answers:

5√26

5

2√5

5√2

√26

Correct answer:

5√2

Explanation:

First, we need to find the points of intersection between f(x) and g(x) by setting them equal to one another and solving.

f(x) = g(x)

2x2 - 3x + 1 = 13 – x 

Add x to both sides.

2x2 – 2x + 1 = 13

Subtract 13 from both sides.

2x2 – 2x – 12 = 0.

Divide by two to make the coefficients easier to work with.

x2 – x – 6 = 0

Factor.

(x – 3)(x + 2) = 0

Set each of the factors equal to zero and then solve.

x – 3 = 0

x = 3

x + 2 = 0

x = –2

The two functions intersect where x = –2 and where x = 3. 

The question asks us to find the distance between the points of intersection. Therefore, we will need to find the y-coordinates of the points of intersection when x = –2 and when x = 3.

When x = –2, f(–2) = g(–2) = 13 – (–2) = 15.

When x = 3, f(3) = g(3) = 13 – 3 = 10.

Thus, the points of intersection are (–2, 15) and (3, 10).

We can now use the distance formula given below.

Distance

The answer is 5√2

Example Question #222 : Algebra

What is the sum of x and y when you solve the following system of equations:

x – 3y = –5

2x + 5y = 12

Possible Answers:

1

3

5

4

2

Correct answer:

3

Explanation:

We can solve this system of equations by using substitution. Rewriting the first equation, we get x = –5 + 3y. This equation gets substituted into the second equation, then solve for y.  Once we know what y is, we can substitute the value into the first equation to find x. In this case, x = 1 and y = 2.

Example Question #223 : Algebra

Sammy is counting his money when he notices he has two more quarters than dimes and the number of nickels are the same as the sum of quarters and dimes.  The total cash he has on hand is $1.05.  How many quarters does he have?

Possible Answers:

5

7

3

4

1

Correct answer:

3

Explanation:

Define the variables as

x = # of dimes

x + 2 = # of quarters

x + x + 2 = # of nickels

In general, the formula for money problems in V1N1 + V2N2 + V3N3 = $total

0.10x + 0.25(x + 2) + 0.05(2x + 2) = 1.05

Solving the equation we see that there is one dime, three quarters and four nickels.

Example Question #222 : Equations / Inequalities

If x2 – y2 = 20, and x + y = 10, then what is the product of x and y?

Possible Answers:

24

–64

6

–4

–24

Correct answer:

24

Explanation:

This problem involves a system of two equations. The first equation is x2 – y2 = 20, and the second equation is x + y = 10. Let us solve the second equation in terms of y, and then we can substitute this value into the first equation.

x + y = 10

Subtract y from both sides.

x = 10 – y

Substitute 10 - y for x in the first equation.

x2 – y2 = 20

(10 - y)2 – y2 = 20

We can use the FOIL method to find (10 – y)2

(10 – y)2 = (10 – y)(10 – y) = 10(10) – 10y – 10y + y2 = 100 –20y + y2.

Now we can go back to our original equation and replace (10 – y)with 100 – 20y + y2.

(100 – 20y + y2) – y2 = 20

100 – 20y = 20

Subtract 100 from both sides.

–20y = –80

Divide both sides by –20.

y = 4.

Now that we know that y = 4, we can use either of our original two equations to solve for x. Using the equation x + y = 10 is probably simpler.

x + y = 10

x + 4 = 10

x = 6.

The original question asks for the product of x and y, which would be 4(6), which equals 24.

The answer is 24. 

Learning Tools by Varsity Tutors