PSAT Math : Fractions

Study concepts, example questions & explanations for PSAT Math

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Example Questions

Example Question #31 : Fractions

In a classroom of  students, each student takes a language class (and only one—nobody studies two languages).  take Latin,  take Greek,  take Anglo-Saxon, and the rest take Old Norse. What is the ratio of students taking Old Norse to students taking Greek?

Possible Answers:

Correct answer:

Explanation:

To begin, you need to calculate how many students are taking Old Norse. This is:

Now, the ratio of students taking Old Norse to students taking Greek is the same thing as the fraction of students taking Old Norse to students taking Greek, or:

Next, just reduce this fraction to its lowest terms by dividing the numerator and denominator by their common factor of :

This is the same as .

Example Question #1 : How To Express A Fraction As A Ratio

In a garden, there are  pansies,  lilies,  roses, and  petunias. What is the ratio of petunias to the total number of flowers in the garden?

Possible Answers:

Correct answer:

Explanation:

To begin, you need to do a simple addition to find the total number of flowers in the garden:

Now, the ratio of petunias to the total number of flowers in the garden can be represented by a simple division of the number of petunias by . This is:

Next, reduce the fraction by dividing out the common  from the numerator and the denominator:

This is the same as .

Example Question #1 : Complex Fractions

Simplify:

Possible Answers:

Correct answer:

Explanation:

Simplify the numerator and the denominator, then divide, as follows:

Example Question #2 : Complex Fractions

Evaluate:

Possible Answers:

Correct answer:

Explanation:

Simplify the numerator and the denominator, then divide, as follows:

 

Example Question #1 : How To Subtract Complex Fractions

Solve:

Possible Answers:

Correct answer:

Explanation:

First reduce the fraction. We can divide both the numerator and the denominator by 3.

 

Now our expression looks like this:

When you add or subtract fractions, you need to have the same denominator. The lowest common deonminator here is 2. So we need to multiply and solve:

Example Question #113 : Fractions

Mr. Owens spent $7.50 for a dinner buffet. The amount he paid accounted for 3/4 of the money in his wallet. How much money is left in his wallet for other expenses?

Possible Answers:

$1.00

$10.00

$4.00

$2.50

$6.50

Correct answer:

$2.50

Explanation:

If $7.50 is 3/4 of the total, 7.50/3 gives us what 1/4 of his total money would be. This equals $2.50, the remaining unspent quarter.

Example Question #1 : Whole And Part

A certain ball that is dropped will bounce back to 3/5 of the height it was initially dropped from.  If after the 2nd bounce the ball reaches  39.96 ft, what was the initial height the ball was dropped from? 

Possible Answers:

100 ft

66 ft

111 ft

135 ft

150 ft

Correct answer:

111 ft

Explanation:

We know the height of the initial bounce, so work backwards to find the initial height.  39.96/0.6 = 66.6 = height of ball after first bounce

66.6/0.6 = 111 ft

Example Question #122 : Fractions

A pitcher of water is filled \dpi{100} \small \frac{2}{5} of full.  An additional 27 ounces of water is added.  Now the pitcher of water is completely full.  How much water does the pitcher hold?

Possible Answers:

30

45

40

50

35

Correct answer:

45

Explanation:

If \dpi{100} \small 27 ounces fills the pitcher, then it must equal the volume of \dpi{100} \small \frac{3}{5} of the pitcher.  If \dpi{100} \small \frac{3}{5} of a pitcher equals 27 ounces, then \dpi{100} \small \frac{1}{5} of a pitcher equals \dpi{100} \small 27\div 3=9ounces.  Since there are \dpi{100} \small 5 fifths in the pitcher, it must hold \dpi{100} \small 9\times 5=45 ounces total.

Example Question #81 : Fractions

If Mr. Jones’ math class has 8 boys and two-thirds of the class are girls, how many total students are in the class?

 

Possible Answers:

Correct answer:

Explanation:

If two-thirds of the class are girls, then one-third must be boys. Set up an equation comparing the number of boys to how much they represent in the entire class:

8 = (1/3) x, where x is the number in the entire class.

When we solve for x in the equation we get x = 24.

 

 

Example Question #3 : How To Find The Whole From The Part

A certain bakery makes chocolate, vanilla, red velvet, and carrot cupcakes in a ratio of 2:3:5:1. If that bakery makes 63 vanilla cupcakes in one day, what is the total number of cupcakes that the bakery made that day?

Possible Answers:

Correct answer:

Explanation:

Because the bakery makes 63 vanilla cupcakes in one day, start by dividing the 63 by the vanilla part of the ratio, which is 3. . That means that the bakery made 21 times the basic set of 2 chocolate, 3 vanilla, 5 red velvet, and 1 carrot cupcakes.

Now add up the parts of your ratio: . If the bakery only made 3 vanilla cupcakes, then it would have made 11 cupcakes that day. But, because the bakery made 21 times that number of vanilla cupcakes, it made 21 times the total number of cupcakes over the course of the day. To find the total number of cupcakes the bakery made that day, you multiply  to get 

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