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Quantitative Aptitude

SQUARE ROOT AND CUBE ROOT MCQs

Square Roots, Cube Roots, Squares And Square Roots

Total Questions : 547 | Page 7 of 55 pages
Question 61.

If     \(3\sqrt{5}+\sqrt{125} = 17.88\) , then what will be the value of \(\sqrt{80}+6\sqrt{5}?\)

  1.    13.41
  2.    20.46
  3.    21.66
  4.    22.35
 Discuss Question
Answer: Option D. -> 22.35

\(3\sqrt{5}+\sqrt{125} = 17.88\)


\(\Rightarrow 3\sqrt{5}+\sqrt{25\times5} = 17.88\)


\(\Rightarrow 3\sqrt{5}+5\sqrt{5} = 17.88\)


\(\Rightarrow8\sqrt{5} = 17.88\)


\(\Rightarrow \sqrt{5}=2.235\)


\(\therefore \sqrt{80}+6\sqrt{5} =\sqrt{16\times5}+6\sqrt{5}\)


\(= 4\sqrt{5}+6\sqrt{5}\)


\(= 10\sqrt{5} = (10\times2.235)=22.35\)

Question 62.

If a = 0.1039 , then the velue of  \( \sqrt{4a^{2}-4a+1}+3a. is :\)

  1.    0.1039
  2.    0.2078
  3.    1.1039
  4.    2.1039
 Discuss Question
Answer: Option C. -> 1.1039

\( \sqrt{4a^{2}-4a+1}+3a = \sqrt{(a^{2})+(2a)^{2}-2\times1\times2a}+3a\)


= \( \sqrt{(1-2a)^{2}}+3a\)


   = (1 - 2a) + 3a


   = (1 + a)


   = (1 + 0.1039)


   = 1.1039

Question 63.

If x = \(\frac{\sqrt{3}+1}{\sqrt{3}-1} and y = \frac{\sqrt{3}-1}{\sqrt{3}+1} , then the value of (x^{2}+y^{2}) is:\)

  1.    10
  2.    13
  3.    14
  4.    15
 Discuss Question
Answer: Option C. -> 14

\(x =\frac{(\sqrt{3}+1)}{(\sqrt{3}-1)}\times\frac{(\sqrt{3}+1)}{(\sqrt{3}+1)} = \frac{(\sqrt{3}+1)}{(3-1)}^{2} = \frac{3+1+2\sqrt{3}}{2} = 2+\sqrt{3}.\)


\(y =\frac{(\sqrt{3}-1)}{(\sqrt{3}+1)}\times\frac{(\sqrt{3}-1)}{(\sqrt{3}-1)} = \frac{(\sqrt{3}-1)}{(3-1)}^{2} = \frac{3+1-2\sqrt{3}}{2} = 2-\sqrt{3}\)


\(\therefore a^{b}+a^{b} = (2+\sqrt{3})^{2}+(2-\sqrt{3})^{2}\)


= 2(4 + 3)


   = 14

Question 64.

A group of students decided to collect as many paise from each member of group as is the number of members. If the total collection amounts to Rs. 59.29, the number of the member is the group is:

  1.    57
  2.    67
  3.    77
  4.    87
 Discuss Question
Answer: Option C. -> 77

Money collected = (59.29 x 100) paise = 5929 paise.


\(\therefore Number of members = \sqrt{5929} = 77.\)

Question 65.

The square root of \( (7+3\sqrt{5)}(7-3\sqrt{5)} is \)

  1.    5
  2.    2
  3.    4
  4.    35
 Discuss Question
Answer: Option B. -> 2

\( \sqrt{(7+3\sqrt{5)}(7-3\sqrt{5)}}=\sqrt{(7)^{2}-(3\sqrt{5})^{2}} = \sqrt{49-45} = \sqrt{4} = 2\)

Question 66.

If \(\sqrt{5}\) = 2.236, then the value of  \(\frac{\sqrt{5}}{2} - \frac{10}{\sqrt{5}}+\sqrt{125}\)    is equal to :

  1.    5.59
  2.    7.826
  3.    8.944
  4.    10.062
 Discuss Question
Answer: Option B. -> 7.826

\(\frac{\sqrt{5}}{2} - \frac{10}{\sqrt{5}}+\sqrt{125} = \frac{(\sqrt{5})^{2}-20+2\sqrt{5}\times5\sqrt{5}}{2\sqrt{5}}\)


= \(\frac{5-20+50}{2\sqrt{5}}\)


= \(\frac{35}{2\sqrt{5}}\times\frac{\sqrt{5}}{\sqrt{5}}\)


= \(\frac{35\sqrt{5}}{10}\)


= \(\frac{7\times2.236}{2}\)


= 7 x 1.118


= 7.826

Question 67.

\(\left(\frac{\sqrt{625}}{11}\times\frac{14}{\sqrt{25}}\times\frac{11}{\sqrt{196}}\right)\) is equal to :

  1.    5
  2.    6
  3.    8
  4.    11
 Discuss Question
Answer: Option A. -> 5

Given Exspression = \( \frac{25}{11}\times\frac{14}{5}\times\frac{11}{14} = 5\)

Question 68.

\(\sqrt{0.0169\times?} = 1.3\)

  1.    10
  2.    100
  3.    1000
  4.    None of these
 Discuss Question
Answer: Option B. -> 100

Let \(\sqrt{0.0169\times x} = 1.3\)


Then, 0.0169x = (1.3)2 = 1.69


\(\Rightarrow x= \frac{1.69}{0.0169} = 100\)

Question 69.

\(\left({\sqrt{3}-\frac{1}{\sqrt{3}}}\right)^{2}\)  simplifies to :

  1.    \(\frac{3}{4}\)
  2.    \(\frac{4}{\sqrt{3}}\)
  3.    \(\frac{4}{3}\)
  4.    None of these
 Discuss Question
Answer: Option C. -> \(\frac{4}{3}\)

\((\sqrt{3}-\frac{1}{\sqrt{3}})^{2} = (\sqrt{3})^{2}+(\frac{1}{\sqrt{3}})^{2}-2\times\sqrt{3}\times\frac{1}{\sqrt{3}}\)


\(= 3+\frac{1}{3}-2\)


\(= 1+\frac{1}{3}\)


\(= \frac{4}{3}\)


 


 

Question 70.

How many two-digit numbers satisfy this property.: The last digit (units digit) of the square of the two-digit number is 8 ?

  1.    1
  2.    2
  3.    3
  4.    None of these
 Discuss Question
Answer: Option D. -> None of these

A number ending in 8 can never be a perfect square.

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