PSAT Math : Arithmetic

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #111 : Arithmetic

If \dpi{100} \small x=\frac{2}{3} and \dpi{100} \small y= \frac {3}{4}, then what is the value of \dpi{100} \small \frac {x}{y}?

Possible Answers:

\dpi{100} \small \frac{5}{7}

\dpi{100} \small \frac{1}{2}

\dpi{100} \small 2

\dpi{100} \small \frac{9}{8}

\dpi{100} \small \frac{8}{9}

Correct answer:

\dpi{100} \small \frac{8}{9}

Explanation:

Dividing by a number (in this case \dpi{100} \small \frac {3}{4}) is equivalent to multiplying by its reciprocal (in this case \dpi{100} \small \frac {4}{3}).  Therefore:

\dpi{100} \small \frac {2}{3}\div \frac{3}{4} = \frac{2}{3}\times \frac{4}{3} = \frac{8}{9}

Example Question #1 : Operations With Fractions

Evaluate the following:

Possible Answers:

\frac{25}{507}

\frac{507}{400}

None of the available answers

\frac{4}{5}

\frac{400}{507}

Correct answer:

\frac{400}{507}

Explanation:

First we will evaluate the terms in the parentheses:

Next, we will square the first fraction:

\frac{100}{169}\div \frac{3}{4}

We can evaluate the division as such:

\frac{100}{169}\times\frac{4}{3}=\frac{400}{507}

Example Question #2 : How To Divide Fractions

Simplify: 

Possible Answers:

Correct answer:

Explanation:

Start by rewriting this fraction as a division problem:

When dividing fractions, you multiply by the reciprocal of the second fraction, so you can rewrite your problem like this:

Multiply across the numerators and then across the denominators to get . The x's cancel, and you can reduce the fraction to be .

Example Question #3 : How To Divide Fractions

Define an operation  as follows:

For all real numbers ,

.

Evaluate .

Possible Answers:

Correct answer:

Explanation:

, or, equivalently,

Example Question #1 : How To Divide Fractions

Define an operation  as follows:

For all real numbers ,

.

Evaluate .

Possible Answers:

Correct answer:

Explanation:

,

or, equivalently, 

 

Example Question #5 : How To Divide Fractions

Define an operation  as follows:

For all real numbers ,

.

Evaluate .

Possible Answers:

Correct answer:

Explanation:

Example Question #111 : Fractions

Define an operation  as follows:

For all real numbers ,

.

Evaluate .

Possible Answers:

Correct answer:

Explanation:

Example Question #7 : How To Divide Fractions

Define an operation  as follows:

For all real numbers ,

.

Evaluate .

Possible Answers:

The correct answer is not among the other responses.

Correct answer:

Explanation:

or, equivalently,

Example Question #111 : Fractions

Define an operation  as follows:

For all real numbers ,

.

Evaluate .

Possible Answers:

Correct answer:

Explanation:

,

or, equivalently,

From here we need to find a common denominator.

 

 

Example Question #111 : Fractions

Simplify:

Possible Answers:

Correct answer:

Explanation:

Begin by simplifying any additions that need to be done:

becomes

Now, remember that the numerator  can be rewritten :

Now, when you divide fractions, you multiply the numerator by the reciprocal of the denominator:

Cancel the s and you get: 

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