SAT Math : SAT Mathematics

Study concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #1 : How To Find The Lowest / Least Common Denominator

3/5 + 4/7 – 1/3 = 

Possible Answers:

72/89

88/105

7/9

4/3

3/37

Correct answer:

88/105

Explanation:

We need to find a common denominator to add and subtract these fractions. Let's do the addition first. The lowest common denominator of 5 and 7 is 5 * 7 = 35, so 3/5 + 4/7 = 21/35 + 20/35 = 41/35. 

Now to the subtraction. The lowest common denominator of 35 and 3 is 35 * 3 = 105, so altogether, 3/5 + 4/7 – 1/3 = 41/35 – 1/3 = 123/105 – 35/105 = 88/105. This does not simplify and is therefore the correct answer.

Example Question #1 : Lowest Common Denominator

What is the lowest common denominator of the fractions below? 

Possible Answers:

Correct answer:

Explanation:

In order to find the lowest common denominator, you must first list the multiples of each of the denominators of the three fractions:

The lowest common denominator between these three sets of multiples is

Example Question #631 : Arithmetic

What is the Lowest Common Denominator of  ,and ?

Possible Answers:

Correct answer:

Explanation:

The smallest number they all have in common in .

Example Question #151 : Arithmetic

Simplify x/2 – x/5

Possible Answers:

3x/10

5x/3

3x/7

7x/10

2x/7

Correct answer:

3x/10

Explanation:

Simplifying this expression is similar to 1/2 – 1/5.  The denominators are relatively prime (have no common factors) so the least common denominator (LCD) is 2 * 5 = 10.  So the problem becomes 1/2 – 1/5 = 5/10 – 2/10 = 3/10.

Example Question #631 : Arithmetic

If \dpi{100} \small \frac{p}{6} is an integer, which of the following is a possible value of \dpi{100} \small p?

Possible Answers:

\dpi{100} \small 0

\dpi{100} \small 2

\dpi{100} \small 16

\dpi{100} \small 4

\dpi{100} \small 3

Correct answer:

\dpi{100} \small 0

Explanation:

\dpi{100} \small \frac{0}{6}=0, which is an integer (a number with no fraction or decimal part).  All the other choices reduce to non-integers.

Example Question #632 : Arithmetic

Simplify: \frac{4x^{5}y^{3}z}{12x^{3}y^{6}z^{2}}

Possible Answers:

\frac{x^{2}}{3y^{3}z}

\frac{1}{3x^{2}y^{3}z}

\frac{3x^{2}y^{3}}{z}

\frac{x^{2}}{8y^{3}z}

 

 

Correct answer:

\frac{x^{2}}{3y^{3}z}

Explanation:

\frac{4x^{5}y^{3}z}{12x^{3}y^{6}z^{2}}=\frac{x^{2}}{3y^{3}z}

First, let's simplify \frac{4}{12}. The greatest common factor of 4 and 12 is 4. 4 divided by 4 is 1 and 12 divided by 4 is 3. Therefore \frac{4}{12}=\frac{1}{3}.

To simply fractions with exponents, subtract the exponent in the numerator from the exponent in the denominator. That leaves us with \frac{1}{3}x^{2}y^{-3}z^{-1} or \frac{x^{2}}{3y^{3}z}

 

Example Question #1 : How To Simplify A Fraction

Which of the following is not equal to 32/24?

Possible Answers:

160/96

224/168

16/12

96/72

4/3

Correct answer:

160/96

Explanation:

24/32 = 1.33

16/12 =1.33

224/168 =1.33

4/3 = 1.33

96/72 = 1.33

160/96 = 1.67

Example Question #1 : How To Simplify A Fraction

Find the root of

Possible Answers:

Can not be determined

Correct answer:

Explanation:

The root occurs where . So we substitute 0 for .

This means that the root is at .

Example Question #5 : Simplifying Fractions

Simplify the fraction below:

Possible Answers:

Correct answer:

Explanation:

The correct approach to solve this problem is to first write factors for the numerator and the denominator:

The highest common factor is 5. Therefore, you can divide the numerator and denominator by 5 in order to get a simplified fraction. 

Thus the numerator becomes,

 and the denominator becomes .

Therefore the final answer is .

Example Question #2 : How To Simplify A Fraction

Simplify:  

Possible Answers:

Correct answer:

Explanation:

Find the common factors of the numerator and denominator.  They both share factors of 2,4, and 8.  For simplicity, factor out an 8 from both terms and simplify.

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