SAT Math : How to find the whole from the part

Study concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #1 : Whole And Part

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:

$2.50

$6.50

$10.00

$4.00

$1.00

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 #1641 : Psat Mathematics

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

150 ft

135 ft

111 ft

66 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 #10 : Whole And Part

A pitcher of water is filled \dpi{100} \small \frac{2}{5}\(\displaystyle \dpi{100} \small \frac{2}{5}\) 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:

40

35

45

50

30

Correct answer:

45

Explanation:

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

Example Question #11 : Whole And Part

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:

\(\displaystyle 16\)

\(\displaystyle 24\)

\(\displaystyle 12\)

\(\displaystyle 27\)

\(\displaystyle 30\)

Correct answer:

\(\displaystyle 24\)

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 #2 : How To Find The Whole From The Part

\(\displaystyle 6\) is what \(\displaystyle 30\%\) of what? 

Possible Answers:

\(\displaystyle 25\)

\(\displaystyle 60\)

\(\displaystyle 15\)

\(\displaystyle 20\)

\(\displaystyle 30\)

Correct answer:

\(\displaystyle 20\)

Explanation:

With the given information, we can set up a proportion. 

\(\displaystyle \frac{6}{x}=\frac{30}{100}\)

\(\displaystyle 30x=600\)

\(\displaystyle x=20\)

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