SAT Math : Arithmetic

Study concepts, example questions & explanations for SAT Math

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Example Questions

Example Question #4 : How To Find Percentage

What percent of 250 is 20?

Possible Answers:

\(\displaystyle 8\%\)

\(\displaystyle 5\%\)

\(\displaystyle 12\%\)

\(\displaystyle 15\%\)

\(\displaystyle 10\%\)

Correct answer:

\(\displaystyle 8\%\)

Explanation:

Verbal cues include "of" and "is."  Of means multiplication and is means equals

The equation to solve becomes \(\displaystyle 0.01\cdot x\cdot 250 = 20\) so \(\displaystyle x = 8\%\)

Example Question #11 : Other Percentage

What number is 30% of 90?

Possible Answers:

\(\displaystyle 15\)

\(\displaystyle 27\)

\(\displaystyle 30\)

\(\displaystyle 36\)

\(\displaystyle 45\)

Correct answer:

\(\displaystyle 27\)

Explanation:

Verbal cues include "is" and "of."  "Is" means equals and "of" means multiplication.

So the equation to solve becomes \(\displaystyle x = 0.30\cdot 90 = 27\)

Example Question #12 : Other Percentage

If the length of a rectangle is increased by 50% and with width of the same rectangle is decreased by 50%, what is the effect on the area of the rectangle? 

Possible Answers:

It is decreased by 50%

It is decreaed by 25%

It is increased by 25%

It is increased by 50%

It is unchanged

Correct answer:

It is decreaed by 25%

Explanation:

This is a good question to use random numbers. Lets use 100 and 10 as the lengths. That means the area = 100 x 10 = 1000

If we increase the length of the side measuring 100 by 50% = 150

If we decrease the length of the other side 50% = 5

Area = 150 x 5 = 750

We see that the area decreased by 250 or 25% decrease in area!

Example Question #13 : Other Percentage

If 80 percent of x is 200, what is 60 percent x?

Possible Answers:

250

150

225

175

200

Correct answer:

150

Explanation:

.80x=200\(\displaystyle .80x=200\)

x=200/.80\(\displaystyle x=200/.80\)

x=250\(\displaystyle x=250\)

.60 (x) = ?\(\displaystyle .60 (x) = ?\)

.60 (250) = 150\(\displaystyle .60 (250) = 150\)

Example Question #14 : Other Percentage

Seventeen percent of some number is 34. What is this number?

Possible Answers:

\(\displaystyle 3417\)

\(\displaystyle 485\)

\(\displaystyle 200\)

None of the available answers

\(\displaystyle 1700\)

Correct answer:

\(\displaystyle 200\)

Explanation:

The algebraic expression is:

\(\displaystyle 0.17x=34\)

\(\displaystyle x=\frac{34}{0.17}\times\frac{100}{100}=\frac{3400}{17}=200\)

Example Question #271 : Arithmetic

What number is 125% of 60?

Possible Answers:

66

80

75

90

60

Correct answer:

75

Explanation:

Translate this into a mathematical equation:

x = 1.25 * 60

x = 75

Example Question #11 : Other Percentage

If 10% of x\(\displaystyle x\) is equal to 25% of y\(\displaystyle y\), and y=16\(\displaystyle y=16\), what is the value of x\(\displaystyle x\)?

Possible Answers:

24\(\displaystyle 24\)

4\(\displaystyle 4\)

6.4\(\displaystyle 6.4\)

40\(\displaystyle 40\)

64\(\displaystyle 64\)

Correct answer:

40\(\displaystyle 40\)

Explanation:

Find 25% of y\(\displaystyle y\):

16 \cdot 0.25 = 4\(\displaystyle 16 \cdot 0.25 = 4\)

10% of x\(\displaystyle x\) is equal to 4. Therefore, 0.1x = 4\(\displaystyle 0.1x = 4\).

Divide both sides by 0.1 to find that x = 40\(\displaystyle x = 40\).

Example Question #12 : Fractions And Percentage

There are \(\displaystyle 48\) registered students in the math club. Students are deciding what activity they could do for their end of semester event. They have three choices: rock climbing, bowling, or outdoor laser tag. \(\displaystyle 14\) students vote for rock climbing, \(\displaystyle 12\) students vote for bowling, and \(\displaystyle 16\) students vote for outdoor laser tag.

What percent of students did not vote?

Possible Answers:

\(\displaystyle 13.5\%\)

\(\displaystyle 12.5\%\)

\(\displaystyle 0\%\)

\(\displaystyle 14.5\%\)

\(\displaystyle 11.5\%\)

Correct answer:

\(\displaystyle 12.5\%\)

Explanation:

The number of students who did not vote is:

\(\displaystyle 48-14-12-16=6\)

The percent of students who did not vote is therefore:

\(\displaystyle \frac{6}{48}=\frac{1}{8}=0.125\)

\(\displaystyle 12.5\%\) of the students did not vote.

Example Question #17 : How To Find Percentage

Joaquin is running for Prom King.  If he receives \(\displaystyle 30\%\) of the votes from a senior class of \(\displaystyle 200\) students, and \(\displaystyle 60\%\) of the votes from a junior class of \(\displaystyle 250\) students, how many votes did he receive in total?

Possible Answers:

\(\displaystyle 195\)

\(\displaystyle 270\)

\(\displaystyle 202\)

\(\displaystyle 135\)

\(\displaystyle 210\)

Correct answer:

\(\displaystyle 210\)

Explanation:

First, we find how many seniors voted for him:

0.30 * 200 = 60 seniors

Then we find how many juniors using the same method

0.60 * 250 = 150 Juniors

Finally, we add the two together

60 + 150 = 210 students total

Example Question #18 : How To Find Percentage

13 is what percent of 25? 

Possible Answers:

\(\displaystyle 50\%\)

\(\displaystyle 45\%\)

\(\displaystyle 60\%\)

\(\displaystyle 20\%\)

\(\displaystyle 52\%\)

Correct answer:

\(\displaystyle 52\%\)

Explanation:

To solve this problem, we should set up the following proportion

\(\displaystyle \frac{13}{25}=\frac{x}{100}\)

where x is the percentage we are looking for.

To solve, simply cross multiply and solve for x.

\(\displaystyle 1300=25x\)

\(\displaystyle x=52\)

Therefore, our answer is 52%.

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