Square and Cube Roots Quiz Set 016

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Question 1

What is cube root of 0.000512?

 A

0.08.

 B

0.16.

 C

0.016.

 D

1.6.

Soln.
Ans: a

We can see that 0.08 × 0.08 × 0.08 = 0.000512, so cube root is 0.08.


Question 2

What is the least number that should be subtracted from 0.0449 to make it a perfect square?

 A

0.04.

 B

0.06.

 C

0.05.

 D

0.004.

Soln.
Ans: a

We know that 0.07 = $√0.0049$, so by inspection we can see that 0.0449 - 0.04 will give us 0.0049.


Question 3

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 4

What is the value of $√{(13 - 3√5) × (13 + 3√5)}$?

 A

$√124$.

 B

$√248$.

 C

$√196$.

 D

$√416$.

Soln.
Ans: a

By inspection, we can easily see that the formula (a - b) × (a + b) can be used to simplify like this: $√{(13)^2 - (3√5)^2}$, which is same as $√{169 - (3^2 × 5)}$, which is same as $√{169 - 45}$ = $√124$.


Question 5

If x = 0.2054, then what is the value of $8x + √{16x^2 - 8x + 1}$?

 A

1.82.

 B

1.414.

 C

2.236.

 D

1.732.

Soln.
Ans: a

By inspection, $8x + √{16x^2 - 8x + 1}$ is same as $8x + √{({1 - 4x})^2}$, which is same as 8x + (1 - 4x) = 1 + 4x = 1.82.


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Creative Commons License
This Blog Post/Article "Square and Cube Roots Quiz Set 016" 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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