PSAT Math : PSAT Mathematics

Study concepts, example questions & explanations for PSAT Math

varsity tutors app store varsity tutors android store

Example Questions

Example Question #1321 : Psat Mathematics

Solve for \(\displaystyle x\).

\frac{1}{3}(3x-6)+\frac{1}{2}(2x+4)=\frac{1}{5}(15x -5)\(\displaystyle \frac{1}{3}(3x-6)+\frac{1}{2}(2x+4)=\frac{1}{5}(15x -5)\)

Possible Answers:

2\(\displaystyle 2\)

-2\(\displaystyle -2\)

-3\(\displaystyle -3\)

0\(\displaystyle 0\)

\(\displaystyle 1\)

Correct answer:

\(\displaystyle 1\)

Explanation:

First distribute the fractions:

\(\displaystyle x-2 +x+2 =3x-1\)

Combine like terms:

\(\displaystyle 2x=3x-1\)

\(\displaystyle x=1\)

Example Question #1322 : Psat Mathematics

Solve for x\(\displaystyle x\).

(2x+3)-3(x+5)=-(3x-4)\(\displaystyle (2x+3)-3(x+5)=-(3x-4)\)

Possible Answers:

\(\displaystyle 8\)

0\(\displaystyle 0\)

-4\(\displaystyle -4\)

-8\(\displaystyle -8\)

4\(\displaystyle 4\)

Correct answer:

\(\displaystyle 8\)

Explanation:

First distribute to eliminate the parentheses:

2x+3-3x-15=-3x+4\(\displaystyle 2x+3-3x-15=-3x+4\)

Then combine like terms:

2x=16\(\displaystyle 2x=16\) 

x=8\(\displaystyle x=8\)

Example Question #1323 : Psat Mathematics

x = 1/2

What does 1/x + 1/(x + 4) equal?

Possible Answers:

4

20

20/9

9/2

4/9

Correct answer:

20/9

Explanation:

1/x + 1/(x+4) =

1/(1/2) + 1/ (1/2 + 4) =

1/ (1/2) + 1 / (9/2)  =

2 + 2/9

20/9

Example Question #1 : How To Solve For A Variable As Part Of A Fraction

Solve for \(\displaystyle x\).

\(\displaystyle \frac{16}{x + 7} = \frac{2}{6}\)

Possible Answers:

\(\displaystyle 36\)

\(\displaystyle 41\)

\(\displaystyle 12\)

\(\displaystyle 24\)

\(\displaystyle 28\)

Correct answer:

\(\displaystyle 41\)

Explanation:

Cross multiply. \(\displaystyle 96 = 2 (x+7)\)

Dsitribute. \(\displaystyle 96 = 2x + 14\)

Solve for \(\displaystyle x\). \(\displaystyle 96 - 14 = 2x\)

\(\displaystyle 82 = 2x\)

\(\displaystyle 41 = x\)

Example Question #1324 : Psat Mathematics

If \(\displaystyle x=-5\), what is the value of \(\displaystyle \frac{x^{2}+20}{x-4}\)?

Possible Answers:

\(\displaystyle 25\)

\(\displaystyle -5\)

\(\displaystyle 9\)

\(\displaystyle 45\)

Correct answer:

\(\displaystyle -5\)

Explanation:

To solve this question, substitute -5 in for x in the numerator and denominator. Remember that the square of a negative number is positive.

45 / -9 = -5

 

Example Question #1 : How To Solve For A Variable As Part Of A Fraction

If \(\displaystyle \frac{6}{x}=\frac{9}{19}\) , then what is the value of \(\displaystyle x\)?

Possible Answers:

none of these

38/3

3/38

9/114

7/12

Correct answer:

38/3

Explanation:

cross multiply:

(6)(19) = 9x

114=9x

x = 38/3

Example Question #1 : How To Solve For A Variable As Part Of A Fraction

\dpi{100} \small \frac{4 }{x} = \frac{2}{25}\(\displaystyle \dpi{100} \small \frac{4 }{x} = \frac{2}{25}\)

Find x.

Possible Answers:

\dpi{100} \small 50\(\displaystyle \dpi{100} \small 50\)

None

\dpi{100} \small 0.25\(\displaystyle \dpi{100} \small 0.25\)

\dpi{100} \small \frac{25}{8}\(\displaystyle \dpi{100} \small \frac{25}{8}\)

\dpi{100} \small \frac{8}{25}\(\displaystyle \dpi{100} \small \frac{8}{25}\)

Correct answer:

\dpi{100} \small 50\(\displaystyle \dpi{100} \small 50\)

Explanation:

Cross multiply:

\dpi{100} \small 4 \times 25 = 2x\(\displaystyle \dpi{100} \small 4 \times 25 = 2x\)

\dpi{100} \small 100 = 2x\(\displaystyle \dpi{100} \small 100 = 2x\)

\dpi{100} \small x = 50\(\displaystyle \dpi{100} \small x = 50\)

Example Question #1 : How To Solve For A Variable As Part Of A Fraction

The numerator of a fraction is the sum of 4 and 5 times the denominator. If you divide the fraction by 2, the numerator is 3 times the denominator. Find the simplified version of the fraction.

Possible Answers:

\(\displaystyle 12\)

\(\displaystyle 6\)

\(\displaystyle \frac{1}{2}\)

\(\displaystyle \frac{1}{3}\)

\(\displaystyle 18\)

Correct answer:

\(\displaystyle 6\)

Explanation:

Let numerator = N and denominator = D.

According to the first statement, 

N = (D x 5) + 4.

According to the second statement, N / 2 = 3 * D. 

Let's multiply the second equation by –2 and add itthe first equation:

–N = –6D

+[N = (D x 5) + 4]

=

–6D + (D x 5) + 4 = 0

–1D + 4 = 0

D = 4

Thus, N = 24.

Therefore, N/D = 24/4 = 6.

Example Question #1325 : Psat Mathematics

Solve for \(\displaystyle x\):

\(\displaystyle \frac{24x-8}{3}=12\)

Possible Answers:

\(\displaystyle 3\frac{1}{4}\)

\(\displaystyle \frac{1}{5}\)

\(\displaystyle 2\frac{7}{8}\)

\(\displaystyle 1\frac{5}{6}\)

\(\displaystyle 2\)

Correct answer:

\(\displaystyle 1\frac{5}{6}\)

Explanation:

Solve for \(\displaystyle x\):

\(\displaystyle \frac{24x-8}{3}=12\)

Step 1: Cross-multiply to eliminate the fraction

\(\displaystyle 3(\frac{24x-8}{3})=12 \cdot 3\)

\(\displaystyle 24x-8 = 36\)

Step 2: Solve for \(\displaystyle x\):

\(\displaystyle 24x=44\)

\(\displaystyle x=\frac{44}{24}=\frac{22}{12}=\frac{11}{6}=1\frac{5}{6}\)

Example Question #1 : Data Analysis

This semester, Mary had five quizzes that were each worth 10% of her grade. She scored 89, 74, 84, 92, and 90 on those five quizzes. Mary also scored a 92 on her midterm that was worth 25% of her grade, and a 91 on her final that was also worth 25% of her class grade. What was Mary's final grade in the class?

Possible Answers:

93

85

89

87

91

Correct answer:

89

Explanation:

To find her average grade for the class, we need to multiply Mary's test scores by their corresponding weights and then add them up.

The five quizzes were each worth 10%, or 0.1, of her grade, and the midterm and final were both worth 25%, or 0.25.

average = (0.1 * 89) + (0.1 * 74) + (0.1 * 84) + (0.1 * 92) + (0.1 * 90) + (0.25 * 92) + (0.25 * 91) = 88.95 = 89. 

Looking at the answer choices, they are all spaced 2 percentage points apart, so clearly the closest answer choice to 88.95 is 89.

Learning Tools by Varsity Tutors