ISEE Middle Level Quantitative : Squares / Square Roots

Study concepts, example questions & explanations for ISEE Middle Level Quantitative

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Example Questions

Example Question #1 : How To Find The Square Root

Give the square root of 256.

Possible Answers:

\(\displaystyle 14\)

\(\displaystyle 22\)

\(\displaystyle 16\)

\(\displaystyle 24\)

\(\displaystyle 18\)

Correct answer:

\(\displaystyle 16\)

Explanation:

\(\displaystyle 16\cdot16= 256\) - that is, 16 squared is 256, making 16 the square root of 256 by definition.

Example Question #2 : Squares / Square Roots

Which is the greater quantity?

(a) \(\displaystyle \sqrt{425 }\)

(b) \(\displaystyle 21\)

Possible Answers:

(a) and (b) are equal

(a) is greater

(b) is greater

It is impossible to tell from the information given

Correct answer:

(b) is greater

Explanation:

 \(\displaystyle 21^{2} = 21 \times 21 = 441\), so \(\displaystyle 21 = \sqrt{441}\)

\(\displaystyle 441 > 425\), so 

\(\displaystyle 21 = \sqrt{441} > \sqrt{425}\)

Example Question #3 : Squares / Square Roots

Which is the greater quantity?

(a) \(\displaystyle 6 \sqrt{ 7}\)

(b) \(\displaystyle 7 \sqrt{6}\)

Possible Answers:

(a) is greater

It is impossible to tell from the information given

(a) and (b) are equal

(b) is greater

Correct answer:

(b) is greater

Explanation:

(a) \(\displaystyle \left (6 \sqrt{7} \right )^{2} = 6^{2}\left ( \sqrt{7} \right ) ^{2} = 36 \cdot 7 = 252\), so \(\displaystyle 6 \sqrt{7} = \sqrt{ 252 }\) 

(b) \(\displaystyle \left (7 \sqrt{6} \right )^{2} = 7^{2}\left ( \sqrt{6} \right ) ^{2} = 49 \cdot 6 = 294\), so \(\displaystyle 7\sqrt{6} = \sqrt{ 294 }\)

\(\displaystyle 294 > 252\),  

so 

\(\displaystyle \sqrt{294 }> \sqrt{252}\),

and 

\(\displaystyle 7\sqrt{6} > 6 \sqrt{7}\)

Example Question #3 : Squares / Square Roots

Column A     Column B       

\(\displaystyle \sqrt{100}\)         \(\displaystyle \sqrt{10.0}\)

 

Possible Answers:

There is no relationship between the quantities.

The quantities are equal.

The quantity in Column A is greater.

The quantity in Column B is greater.

Correct answer:

The quantity in Column A is greater.

Explanation:

The square root of 100 is 10, while the square root of 10 is between the square root of 9 and 16, so about 4. Therefore, Column A has to be greater.

Example Question #193 : Isee Middle Level (Grades 7 8) Quantitative Reasoning

Which of the following is equal to \(\displaystyle \sqrt{5^{2}+7^{2}+7}\) ?

Possible Answers:

None of the other responses is correct.

\(\displaystyle 8\)

\(\displaystyle 11\)

\(\displaystyle 10\)

\(\displaystyle 9\)

Correct answer:

\(\displaystyle 9\)

Explanation:

\(\displaystyle \sqrt{5^{2}+7^{2}+7}\)

\(\displaystyle =\sqrt{25 +49+7}\)

\(\displaystyle =\sqrt{81}\)

\(\displaystyle =9\)

Example Question #6 : Squares / Square Roots

Which of the following is equal to \(\displaystyle \sqrt{11^{2}+ 6 \cdot 8}\) ?

Possible Answers:

None of the other responses is correct.

\(\displaystyle 15\)

\(\displaystyle 13\)

\(\displaystyle 14\)

\(\displaystyle 12\)

Correct answer:

\(\displaystyle 13\)

Explanation:

\(\displaystyle \sqrt{11^{2}+ 6 \cdot 8}\)

\(\displaystyle = \sqrt{121+ 6 \cdot 8}\)

\(\displaystyle = \sqrt{121+ 48}\)

\(\displaystyle = \sqrt{169}\)

\(\displaystyle =13\)

Example Question #194 : Isee Middle Level (Grades 7 8) Quantitative Reasoning

Which of the following is equal to \(\displaystyle \sqrt{2^{3}+ 6^{2}+10^{2}}\) ?

Possible Answers:

\(\displaystyle 12\)

None of the other responses is correct.

\(\displaystyle 13\)

\(\displaystyle 11\)

\(\displaystyle 14\)

Correct answer:

\(\displaystyle 12\)

Explanation:

\(\displaystyle \sqrt{2^{3}+ 6^{2}+10^{2}}\)

\(\displaystyle =\sqrt{8+36 +100}\)

\(\displaystyle =\sqrt{ 144}\)

\(\displaystyle =12\)

Example Question #8 : Squares / Square Roots

\(\displaystyle V^{2} = 72\)\(\displaystyle V\) is positive.

Which is the greater quantity?

(a) \(\displaystyle V\)

(b) \(\displaystyle 8\)

Possible Answers:

(A) is greater

It is impossible to tell which is greater from the information given

(B) is greater

(A) and (B) are equal

Correct answer:

(A) is greater

Explanation:

Since \(\displaystyle V\)is positive, we can compare \(\displaystyle V\) to 8 by comparing their squares. 

\(\displaystyle V^{2} = 72\) and \(\displaystyle 8^{2} = 8 \times 8 = 64\)

\(\displaystyle V^{2} > 8^{2}\), so \(\displaystyle V>8\), making (A) greater.

Example Question #4 : Squares / Square Roots

\(\displaystyle F^{2}= 36\)

Which is the greater quantity?

(A) \(\displaystyle F\)

(B) \(\displaystyle 4\)

Possible Answers:

(B) is greater

(A) and (B) are equal

(A) is greater

It is impossible to tell which is greater from the information given

Correct answer:

It is impossible to tell which is greater from the information given

Explanation:

If \(\displaystyle F^{2} = 36\), then one of two things is true - either \(\displaystyle F = 6\) or \(\displaystyle F = -6\).

However, \(\displaystyle 6 > 4\) and \(\displaystyle -6< 4\), so it is impossibe to tell whether (A) or (B) is greater.

Example Question #5 : Squares / Square Roots

\(\displaystyle Q^{2} = 49\)

Which is the greater quantity?

(A) \(\displaystyle Q\)

(B) \(\displaystyle -8\)

Possible Answers:

It is impossible to tell which is greater from the information given

(B) is greater

(A) and (B) are equal

(A) is greater

Correct answer:

(A) is greater

Explanation:

If \(\displaystyle Q^{2} = 49\), then one of two things is true - either \(\displaystyle Q=7\) or \(\displaystyle Q=- 7\). Since \(\displaystyle 7 > -8\) and \(\displaystyle -7 > -8\)\(\displaystyle Q > -8\) either way, so (A) is greater.

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