SSAT Upper Level Math : Number Concepts and Operations

Study concepts, example questions & explanations for SSAT Upper Level Math

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Example Questions

Example Question #2 : How To Divide Square Roots

Simplify by rationalizing the denominator:

\displaystyle \frac{3\sqrt{2}+2\sqrt{3}}{\sqrt{6}}

Possible Answers:

\displaystyle \frac{9\sqrt{3}+4 \sqrt{2} }{9}

\displaystyle \sqrt{3}+ \sqrt{2}

\displaystyle \frac{9\sqrt{3}+4 \sqrt{2} }{6}

\displaystyle \frac{9\sqrt{3}+4 \sqrt{2} }{4}

\displaystyle \frac{\sqrt{3}+ \sqrt{2}}{2}

Correct answer:

\displaystyle \sqrt{3}+ \sqrt{2}

Explanation:

Multiply both numerator and denominator by \displaystyle \sqrt{6}:

\displaystyle \frac{3\sqrt{2}+2\sqrt{3}}{\sqrt{6}}

\displaystyle = \frac{(3\sqrt{2}+2\sqrt{3})\cdot \sqrt{6}}{\sqrt{6}\cdot \sqrt{6}}

\displaystyle = \frac{3\sqrt{2}\cdot \sqrt{6}+2\sqrt{3}\cdot \sqrt{6}}{6}

\displaystyle = \frac{3\sqrt{12} +2\sqrt{18} }{6}

\displaystyle = \frac{3\cdot \sqrt{4} \cdot \sqrt{3}+2\cdot \sqrt{9}\cdot \sqrt{2} }{6}

\displaystyle = \frac{3\cdot 2 \cdot \sqrt{3}+2\cdot3 \cdot \sqrt{2} }{6}

\displaystyle = \frac{6 \cdot \sqrt{3}+6 \cdot \sqrt{2} }{6}

\displaystyle = \sqrt{3}+ \sqrt{2}

Example Question #2 : How To Divide Square Roots

Divide:  \displaystyle \frac{\sqrt{64}}{\sqrt{8}} 

Possible Answers:

\displaystyle 8

\displaystyle \frac{\sqrt2}{4}

\displaystyle 1

\displaystyle \frac{1}{8}

\displaystyle 2\sqrt2

Correct answer:

\displaystyle 2\sqrt2

Explanation:

The values are of the same power.  Divide the terms.

\displaystyle \frac{\sqrt{64}}{\sqrt{8}}= \sqrt{\frac{64}{8}}= \sqrt{8} = \sqrt{4}\times \sqrt{2}= 2\sqrt2

The correct answer is:   \displaystyle 2\sqrt2

Example Question #51 : Number Concepts And Operations

Evan wants to tip approximately  on a \displaystyle \$78.45 restaurant tab. Which of the following comes closest to what he should leave?

Possible Answers:

\displaystyle \$22

\displaystyle \$18

\displaystyle \$14

\displaystyle \$16

\displaystyle \$20

Correct answer:

\displaystyle \$16

Explanation:

The tab can be rounded to \displaystyle \$80 is equal to \displaystyle 0.20.

\displaystyle =\frac{20}{100}=0.20

Now we can multiply the percent by the total amount.

\displaystyle 0.20 * 80 = 16

\displaystyle \$16 is the most reasonable estimate of the recommended tip.

Example Question #1 : Estimation

If the number \displaystyle 50,467 is rounded to the nearest hundredth, which of the following expressions would be equal to that value?

Possible Answers:

\displaystyle 505\cdot100

\displaystyle 504\cdot100

\displaystyle 504.7\cdot100

\displaystyle 505\cdot10

\displaystyle 505\cdot1,000

Correct answer:

\displaystyle 505\cdot100

Explanation:

If \displaystyle 50,467 is rounded to the nearest hundredth, the result will be \displaystyle 50,500

Given that \displaystyle 505\cdot100=50,500, the correct answer is \displaystyle 505\cdot100

Example Question #1 : How To Estimate

Estimate the product \displaystyle 437 \times 877 \times 551 by rounding each factor to the nearest hundred, then multiplying.

Possible Answers:

\displaystyle 192,000,000

\displaystyle 270,000,000

\displaystyle 211,000,000

\displaystyle 180,000,000

\displaystyle 216,000,000

Correct answer:

\displaystyle 216,000,000

Explanation:

437 rounded to the nearest hundred is 400.

877 rounded to the nearest hundred is 900.

551 rounded to the nearest hundred is 600.

Multiply the three whole multiples of 100 to get the desired estimate:

\displaystyle 437 \times 877 \times 551 \approx 400 \times 900 \times 600 = 216,000,000

 

Example Question #2 : How To Estimate

Estimate the product \displaystyle 5 \frac{3}{7}\times 9\frac{3}{5} \times 4\frac{4}{5} by rounding each factor to the nearest unit, then multiplying.

Possible Answers:

\displaystyle 225

\displaystyle 180

\displaystyle 250

\displaystyle 240

\displaystyle 300

Correct answer:

\displaystyle 250

Explanation:

\displaystyle 5 \frac{3}{7} < 5\frac{1}{2}, so \displaystyle 5 \frac{3}{7}  rounded to the nearest unit is 5.

\displaystyle 9\frac{3}{5} \geq 9\frac{1}{2}, so \displaystyle 9\frac{3}{5}  rounded to the nearest unit is 10.

\displaystyle 4\frac{4}{5} \geq 4\frac{1}{2}, so \displaystyle 4\frac{4}{5}  rounded to the nearest unit is 5.

Multiply the three whole numbers to get the desired estimate:

\displaystyle 5 \frac{3}{7}\times 9\frac{3}{5} \times 4\frac{4}{5} \approx 5 \times 10 \times 5 = 250

Example Question #1 : How To Estimate

Estimate the result \displaystyle 8.19 \times 4.87 + 3.27 \times 7.42 by first rounding each number to the nearest unit.

Possible Answers:

\displaystyle 61

\displaystyle 77

\displaystyle 53

\displaystyle 56

\displaystyle 64

Correct answer:

\displaystyle 61

Explanation:

8.19 rounded to the nearest unit is 8.

4.87 rounded to the nearest unit is 5

3.27 rounded to the nearest unit is 3.

7.42 rounded to the nearest unit is 7.

The desired estimate can be found as follows:

\displaystyle 8.19 \times 4.87 + 3.27 \times 7.42

\displaystyle \approx 8 \times 5 + 3 \times 7

\displaystyle =40 + 3 \times 7

\displaystyle =40 + 21 = 61

Example Question #3 : How To Estimate

Estimate the result \displaystyle 8 \frac{2}{7}\times 9\frac{4}{5}+ 3\frac{4}{5} \times 6\frac{2}{5} by first rounding each number to the nearest unit.

Possible Answers:

\displaystyle 104

\displaystyle 544

\displaystyle 106

\displaystyle 90

\displaystyle 504

Correct answer:

\displaystyle 104

Explanation:

\displaystyle 8 \frac{2}{7} < 8\frac{1}{2}, so \displaystyle 8 \frac{2}{7} rounded to the nearest unit is 8.

\displaystyle 9\frac{4}{5} \ge 9\frac{1}{2}, so \displaystyle 9\frac{4}{5} rounded to the nearest unit is 10.

\displaystyle 3\frac{4}{5} \ge 3\frac{1}{2}, so \displaystyle 3\frac{4}{5} rounded to the nearest unit is 4.

\displaystyle 6\frac{2}{5} < 6\frac{1}{2}, so \displaystyle 6\frac{2}{5} rounded to the nearest unit is 6.

The desired estimate can be found as follows:

\displaystyle 8 \frac{2}{7}\times 9\frac{4}{5}+ 3\frac{4}{5} \times 6\frac{2}{5}

\displaystyle \approx 8 \times 10 + 4 \times 6

\displaystyle = 80 + 4 \times 6

\displaystyle = 80 + 24 = 104

Example Question #2 : How To Estimate

Melissa is trying to come up with a reasonable estimate of the amount she spent on groceries over the last six months. She notices that the six checks she wrote out to the local grocery store are in the following amounts: $187.54, $218.89, $174.74, $104.76, $189.75, and $228.64. By estimating each of the amounts of the checks to the nearest ten dollars, come up with a reasonable estimate for Melissa's total expenditure for groceries.

Possible Answers:

Correct answer:

Explanation:

Round each of the amounts to the nearest ten dollars as follows:

$187.54 rounds to $190.

$218.89 rounds to $220.

$174.74 rounds to $170.

$104.76 rounds to $100.

$189.75 rounds to $190.

$228.64 rounds to $230.

Add the rounded figures:

\displaystyle 190+220+170+100+190+230 = 1,100

Example Question #3 : How To Estimate

Estimate the product \displaystyle 8.39 \times 7.34 \times 3.52 by rounding each factor to the nearest unit, then multiplying.

Possible Answers:

\displaystyle 168

\displaystyle 196

\displaystyle 217

\displaystyle 224

\displaystyle 288

Correct answer:

\displaystyle 224

Explanation:

8.39 rounded to the nearest unit is 8 because 0.39 is less than 0.5.

7.34 rounded to the nearest unit is 7 because 0.34 is less than 0.5.

3.52 rounded to the nearest unit is 4 because 0.52 is greater than 0.5.

Multiply the three whole numbers to get the desired estimate:

\displaystyle 8.39 \times 7.34 \times 3.52 \approx 8 \times 7 \times 4 = 56 \times 4 = 224

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