Square and Cube Roots Quiz Set 011

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Question 1

One-half of the cube-root of which number is 0.3?

 A

0.216.

 B

0.256.

 C

0.128.

 D

0.144.

Soln.
Ans: a

Let the number be n. So ${1/2} × √^3n$ = 0.3, which gives $√^3n$ = 2 × 0.3 = 0.6. so n = $0.6^3$ = 0.216.


Question 2

If $√5$ = 2.24, then what is the value of ${√5}/2$ − $2/{√5}$ + $√125$?

 A

11.404.

 B

1.414.

 C

22.414.

 D

0.707

Soln.
Ans: a

The given expression can be simplified to ${{(√5)^2} - {2 × 2} + {2 × √5 × √{5 × 5^2}}}/{2 × √5}$, which is same as ${5 - 4 + 50}/{2 × √5}$, which is same as ${51/{2 × √5}$. Rationalizing, we get ${51/{2 × √5} × {√5/√5}$ which gives ${51√5}/10$ which = 11.404.


Question 3

If $√2$ = 1.41, then what is the value of ${√2}/5$ − $2/{√2}$ + $√8$?

 A

1.697.

 B

1.414.

 C

1.732.

 D

0.707.

Soln.
Ans: a

The given expression can be simplified to ${{(√2)^2} - {5 × 2} + {5 × √2 × √{2 × 2^2}}}/{5 × √2}$, which is same as ${2 - 10 + 20}/{5 × √2}$, which is same as ${12/{5 × √2}$. Rationalizing, we get ${12/{5 × √2} × {√2/√2}$ which gives ${12√2}/10$ which = 1.697.


Question 4

If x = 0.8547, then what is the value of $4x + √{16x^2 - 8x + 1}$?

 A

1.

 B

16.

 C

2.

 D

4.

Soln.
Ans: a

By inspection, $4x + √{16x^2 - 8x + 1}$ is same as $4x + √{({1 - 4x})^2}$, which is same as 4x + (1 - 4x) = 1.


Question 5

What is √0.0004?

 A

0.02.

 B

0.4.

 C

0.2.

 D

0.002.

Soln.
Ans: a

We can see that 0.02 × 0.02 = 0.0004, so square root is 0.02.


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Creative Commons License
This Blog Post/Article "Square and Cube Roots Quiz Set 011" by Parveen (Hoven) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Updated on 2017-04-07.

Posted by Parveen(Hoven),
Aptitude Trainer


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