SAT Math : Fractions

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

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 #2 : Lowest Common Denominator

What is the Lowest Common Denominator of  ,and ?

Possible Answers:

Correct answer:

Explanation:

The smallest number they all have in common in .

Example Question #1 : How To Simplify A Fraction

Simplify x/2 – x/5

Possible Answers:

7x/10

5x/3

2x/7

3x/10

3x/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 #1 : How To Simplify A Fraction

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 16

\dpi{100} \small 0

\dpi{100} \small 2

\dpi{100} \small 3

\dpi{100} \small 4

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 #3 : Simplifying Fractions

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

Possible Answers:

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

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

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

\frac{x^{2}}{3y^{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 #4 : Simplifying Fractions

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

Possible Answers:

16/12

224/168

160/96

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 #1 : Simplifying Fractions

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.

Example Question #7 : Simplifying Fractions

Simply the following fraction: 

Possible Answers:

Correct answer:

Explanation:

Remember that when you divide a fraction by a fraction, that is the same as multiplying the fraction in the numerator by the reciprocal of the fraction in the denominator. 

In other words,

Simplifying this final fraction gives us our correct answer, .

 

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