Square and Cube Roots Quiz Set 001

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Question 1

One-third of the cube-root of which number is 0.6?

 A

5.832.

 B

5.200.

 C

5.414.

 D

5.173.

Soln.
Ans: a

Let the number be n. So ${1/3} × √^3n$ = 0.6, which gives $√^3n$ = 3 × 0.6 = 1.8. so n = $1.8^3$ = 5.832.


Question 2

What is cube root of 0.000008?

 A

0.02.

 B

0.002.

 C

0.2.

 D

0.0002.

Soln.
Ans: a

We can see that 0.02 × 0.02 × 0.02 = 0.000008, so cube root is 0.02.


Question 3

If $2√3 + √27 = 8.66$, then what is the value of $√27 + 4√3$?

 A

12.12.

 B

12.24.

 C

12.00.

 D

12.36.

Soln.
Ans: a

The given expression can be rearranged like this: $2√3 + √{3^{2} × 3}$, which is same as $2√3 + 3√3$ which is same as $5√3 = 8.66$, from which we get $√3 = 1.73$. Next we can see that $√27 + 4√3$ is same as $√{3^{2} × 3} + 4√3$, which is same as $7√3$, which gives $7 × 1.73$ = 12.12.


Question 4

What is the value of ${√17}/6$ − $5/{√17}$?

 A

${-13√17}/102$.

 B

${+13√17}/102$.

 C

${-5√17}/102$.

 D

${+5√17}/102$.

Soln.
Ans: a

The given expression can be simplified to ${{(√17)^2} - 6 × 5}/{6 × √17}$, which is same as ${17 - 30}/{6 × √17}$, which is same as ${-13/{6 × √17}$. Rationalizing, we get ${-13/{6 × √17} × {√17/√17}$ which gives ${-13√17}/102$


Question 5

If $4√5 + √80 = 17.89$, then what is the value of $√125 + 6√5$?

 A

24.60.

 B

12.25.

 C

25.

 D

12.96.

Soln.
Ans: a

The given expression can be rearranged like this: $4√5 + √{4^{2} × 5}$, which is same as $4√5 + 4√5$ which is same as $8√5 = 17.89$, from which we get $√5 = 2.24$. Next we can see that $√125 + 6√5$ is same as $√{5^{2} × 5} + 6√5$, which is same as $11√5$, which gives $11 × 2.24$ = 24.60.


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Creative Commons License
This Blog Post/Article "Square and Cube Roots Quiz Set 001" by Parveen (Hoven) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Updated on 2017-06-24.

Posted by Parveen(Hoven),
Aptitude Trainer


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