SAT Math : Algebra

Study concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #501 : Problem Solving

The sum of the number of pennies and nickels equals 70 and the total dollar amount of the change equals $1.50. How many nickels and pennies are there?

Possible Answers:

20\ pennies,\ 50\ nickels\displaystyle 20\ pennies,\ 50\ nickels

50\ pennies,\ 20\ nickels\displaystyle 50\ pennies,\ 20\ nickels

60\ pennies,\ 10\ nickels\displaystyle 60\ pennies,\ 10\ nickels

None\ of\ the\ answers\displaystyle None\ of\ the\ answers

10\ pennies,\ 60\ nickels\displaystyle 10\ pennies,\ 60\ nickels

Correct answer:

50\ pennies,\ 20\ nickels\displaystyle 50\ pennies,\ 20\ nickels

Explanation:

Assume there are x pennies.  Hence the number of nickels is 70-x\displaystyle 70-x

Now you have to set up an equation for the dollar value of the pennies and nickels which will be x+5(70-x)=150\displaystyle x+5(70-x)=150

Now solving for x\displaystyle x results in x=50\displaystyle x=50 (number of pennies).  Hence the number of nickels will be 70-50=20\displaystyle 70-50=20.

Example Question #23 : How To Simplify An Expression

If \displaystyle log 2 = 0.301, then solve \displaystyle \log \ 32

Possible Answers:

\displaystyle 1.505

\displaystyle 1.431

\displaystyle 1.209

\displaystyle 1.301

\displaystyle 1.612

Correct answer:

\displaystyle 1.505

Explanation:

To solve this problem we use the logarithm rule log (x^{n}) = n log(x)\displaystyle log (x^{n}) = n log(x)

log(32) = log (2^{5}) = 5 log(2)\displaystyle log(32) = log (2^{5}) = 5 log(2) or \displaystyle 1.505

Example Question #791 : Algebra

a=\frac{x^2-y^2}{x-y}\displaystyle a=\frac{x^2-y^2}{x-y}

If both \displaystyle x and \displaystyle y are positive, what is the simplest form of \displaystyle a?

Possible Answers:

x+y\displaystyle x+y

xy\displaystyle xy

x^2-y^2-1\displaystyle x^2-y^2-1

1\displaystyle 1

x-y\displaystyle x-y

Correct answer:

x+y\displaystyle x+y

Explanation:

x^2-y^2\displaystyle x^2-y^2 can also be expressed as (x-y)(x+y))\displaystyle (x-y)(x+y))

a=\frac{(x-y)(x+y)}{x-y}=x+y\displaystyle a=\frac{(x-y)(x+y)}{x-y}=x+y

Example Question #792 : Algebra

Which of the following does not simplify to \displaystyle x?

Possible Answers:

\displaystyle \frac{x(4x)}{4x}

\displaystyle (3-3)x

\displaystyle 5x-(6x-2x)

All of these simplify to \displaystyle x

\displaystyle (x - 1)(x + 2) - x^2 + 2

Correct answer:

\displaystyle (3-3)x

Explanation:

5x – (6x – 2x) = 5x – (4x) = x

(x – 1)(x + 2) - x2 + 2 = x2 + x – 2 – x2 + 2 = x

x(4x)/(4x) = x

(3 – 3)x = 0x = 0

Example Question #793 : Algebra

Edward is \displaystyle e years old. He is 5 years younger than his sister Francine. In terms of \displaystyle e, how old will Francine be in 2 years?

Possible Answers:

\displaystyle e+3

\displaystyle e+7

\displaystyle e+4

\displaystyle e-3

\displaystyle e-7

Correct answer:

\displaystyle e+7

Explanation:

Let f = Francine's age now.  

ef – 5

f+ 5

In 2 years, Francine will be f + 2. Use our previous calculation to substitute.

f + 2 = (e + 5) + 2 = e + 7

Example Question #402 : Gre Quantitative Reasoning

a # b = (a * b) + a

What is 3 # (4 # 1)?

Possible Answers:

8

15

12

27

20

Correct answer:

27

Explanation:

Work from the "inside" outward.  Therefore, first solve 4 # 1 by replacing a with 4 and b with 1:

4 # 1 = (4 * 1) + 4 = 4 + 4 = 8

That means: 3 # (4 # 1) = 3 # 8.  Solve this now:

3 # 8 = (3 * 8) + 3 = 24 + 3 = 27

Example Question #1 : Simplifying Expressions

Simplify the result of the following steps, to be completed in order:

1. Add 7x to 3y

2. Multiply the sum by 4

3. Add x to the product

4. Subtract x – y from the sum

Possible Answers:

28x + 13y

28x + 12y

28x + 11y

29x + 13y

28x – 13y

Correct answer:

28x + 13y

Explanation:

Step 1: 7x + 3y

Step 2: 4 * (7x + 3y) = 28x + 12y

Step 3: 28x + 12y + x = 29x + 12y

Step 4: 29x + 12y – (x – y) = 29x + 12y – x + y = 28x + 13y

Example Question #1 : Simplifying Expressions

Which is the greater quantity: the median of 5 positive sequential integers or the mean of 5 positive sequential integers?

Possible Answers:

The relationship cannot be determined

The median is greater

The quantities are equal

The mean is greater

Correct answer:

The quantities are equal

Explanation:

If the first integer is \dpi{100} \small n, then \dpi{100} \small n+(n+1)+(n+2)+(n+3)+(n+4)=5n+10

\dpi{100} \small \frac{5n+10}{5}=n+2

This is the same as the median.

Example Question #2 : How To Simplify An Expression

You are told that \dpi{100} \small x can be determined from the expression:

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Determine whether the absolute value of \dpi{100} \small x is greater than or less than 2.

Possible Answers:

\dpi{100} \small |x|>2

The relationship cannot be determined from the information given.

The quantities are equal

\dpi{100} \small |x|<2

Correct answer:

\dpi{100} \small |x|>2

Explanation:

The expression is simplified as follows:

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Since \dpi{100} \small 2^{4}=16 the value of \dpi{100} \small x must be slightly greater for it to be 17 when raised to the 4th power.

Example Question #3 : Simplifying Expressions

Which best describes the relationship between \displaystyle (x+y)^3 and \displaystyle x^3+y^3 if \displaystyle x,y\neq 0?

Possible Answers:

The relationship cannot be determined from the information given.

\displaystyle \small (x+y)^{3}>x^{3}+y^{3}

\displaystyle \small (x+y)^{3}=x^{3}+y^{3}

\displaystyle (x+y)^3< x^3 + y^3

Correct answer:

The relationship cannot be determined from the information given.

Explanation:

Use substitution to determine the relationship.

For example, we could plug in \displaystyle x=2 and \displaystyle y=3.

\displaystyle (x+y)^3=(2+3)^3=5^3=125

\displaystyle x^3+y^3=2^3+3^3=4+9=13

So far it looks like the first expression is greater, but it's a good idea to try other values of x and y to be sure. This time, we'll try some negative values, say, \displaystyle x=-4 and \displaystyle y=-3.

\displaystyle (x+y)^3=(-4+-3)^3=-7^3=-343

\displaystyle x^3+y^3=-4^3+-3^3=-64+-27=-91

This time the first quantity is smaller. Therefore the relationship cannot be determined from the information given.

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