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 #34 : Basic Addition, Subtraction, Multiplication And Division

Simplify by rationalizing the denominator:

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

Possible Answers:

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

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

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

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

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

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 #1 : How To Divide Square Roots

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

Possible Answers:

\(\displaystyle \frac{1}{8}\)

\(\displaystyle 2\sqrt2\)

\(\displaystyle 1\)

\(\displaystyle \frac{\sqrt2}{4}\)

\(\displaystyle 8\)

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 #1 : Estimation

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:

\(\displaystyle \$16\)

\(\displaystyle \$18\)

\(\displaystyle \$22\)

\(\displaystyle \$14\)

\(\displaystyle \$20\)

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 #2 : 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:

\(\displaystyle 505\cdot10\)

\(\displaystyle 504.7\cdot100\)

\(\displaystyle 505\cdot1,000\)

\(\displaystyle 505\cdot100\)

\(\displaystyle 504\cdot100\)

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 : Estimation

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

Possible Answers:

\(\displaystyle 211,000,000\)

\(\displaystyle 192,000,000\)

\(\displaystyle 270,000,000\)

\(\displaystyle 180,000,000\)

\(\displaystyle 216,000,000\)

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 : Estimation

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:

\(\displaystyle 180\)

\(\displaystyle 300\)

\(\displaystyle 240\)

\(\displaystyle 250\)

\(\displaystyle 225\)

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 #3 : Estimation

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:

\(\displaystyle 56\)

\(\displaystyle 61\)

\(\displaystyle 64\)

\(\displaystyle 53\)

\(\displaystyle 77\)

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 #4 : Estimation

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:

\(\displaystyle 90\)

\(\displaystyle 504\)

\(\displaystyle 544\)

\(\displaystyle 104\)

\(\displaystyle 106\)

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 #5 : Estimation

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:

\(\displaystyle \$ 1\textup{,}090\)

\(\displaystyle \$ 1\textup{,}100\)

\(\displaystyle \$ 1\textup{,}130\)

\(\displaystyle \$ 1\textup{,\textup{}}120\)

\(\displaystyle \$ 1\textup{,}110\)

Correct answer:

\(\displaystyle \$ 1\textup{,}100\)

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 #6 : Estimation

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

Possible Answers:

\(\displaystyle 168\)

\(\displaystyle 224\)

\(\displaystyle 288\)

\(\displaystyle 217\)

\(\displaystyle 196\)

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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