Square Root Questions for RRB NTPC PDF
Download RRB NTPC Square Root Questions and Answers PDF. Top 15 RRB NTPC Maths questions based on asked questions in previous exam papers very important for the Railway NTPC exam.
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Question 1: What is the square root of 5041?
a) 79
b) 81
c) 71
d) 69
Question 2: Which of the numbers given below is the square root of 16384?
a) 132
b) 128
c) 118
d) 122
Question 3: The square root of which of the following numbers is irrational?
a) 2916
b) 4489
c) 1024
d) 7840
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Question 4: What is the square root of 9409?
a) 83
b) 87
c) 89
d) 97
Question 5: Square root of 0.9 is equal to
a) 0.03
b) 0.3
c) 0.9487
d) 0.9463
Question 6: The square root of 27225 is:
a) 165
b) 155
c) 175
d) 145
Question 7: Which of the numbers given below is the square root of 15376?
a) 122
b) 124
c) 134
d) 128
Question 8: If the roots of the quadratic equation $x^2 – 8x + 14 = 0$ are a and b, then calculate the ratio of the difference of the squares to the difference of cubes of the roots of the given equation.
a) (2/25)
b) $(2/5)^2$
c) 25/4
d) None of these
Question 9: The Square root of which of the following is a rational number?
a) 2361.96
b) 2758.28
c) 72568.4
d) 62504.9
Question 10: The square root of which of the following is a rational number?
a) 6250.49
b) 1250.49
c) 5768.28
d) 1354.24
Question 11: The square root of $1 + x^2 + \sqrt{1 + x^2 + x^4}$is
a) $\frac{1}{\sqrt2} \left[ \sqrt{1 + x + x^2 } + \sqrt{1 – x + x^2 } \right]$
b) $\frac{1}{\sqrt2} \left[ \sqrt{1 + x + x^2 } – \sqrt{1 – x + x^2 } \right]$
c) $\frac{1}{\sqrt2} \left[ \sqrt{1 + x^2 + x^4 + x^8 }\right] $
d) None of the above
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Question 12: The square root of $27-4\sqrt{35}$ is :
a) $\pm(\sqrt{5}+2\sqrt{7})$
b) $\pm(\sqrt{5}-2\sqrt{7})$
c) $\pm(\sqrt{7}-2\sqrt{5})$
d) $\pm(\sqrt{7}+2\sqrt{5})$
Question 13: Two digit number has its tens digit as 4 less than the thrice of units digit.If the units and tens digits are interchanged then its value decreases by 18. Find the square root of the two digit number ?
a) 4.69
b) 7.28
c) 9.1
d) 8.3
Question 14: The square roots of how many factors of 2250 will be natural numbers?
a) 15
b) 4
c) 5
d) 6
Question 15: What is the square root of $214 – 78\sqrt{5}$
a) $13-3\sqrt{5}$
b) $17-4\sqrt{5}$
c) $13-6\sqrt{5}$
d) $17-3\sqrt{5}$
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Answers & Solutions:
1) Answer (C)
The factors of 5041 are 1, 71 and 5041.
Hence, The square root of 5041 is 71.
2) Answer (B)
16384=2*2*2*2*2*2*2*2*2*2*2*2*2*2
Square root of 16384=2*2*2*2*2*2*2
=128
3) Answer (D)
‘2916’ is the square of 54. It is a perfect square.
‘4489’ is the square of 67. It is a perfect square.
‘1024’ is the square of 32. It is a perfect square.
‘7840’ is not a perfect square and the square root of 7840 is an irrational number.
Hence, option D is the correct answer.
4) Answer (A)
5) Answer (C)
6) Answer (A)
7) Answer (B)
8) Answer (B)
9) Answer (A)
10) Answer (D)
11) Answer (E)
12) Answer (C)
We have to find $27-4\sqrt{35}$
We can write it as :
= $\sqrt{{27} – 2 \times 2\times \sqrt{5} \times \sqrt{7}}$
Since, $(a^2 + b^2 – 2ab) = (a-b)^2$
= $\sqrt{(2\sqrt{5})^2 + (\sqrt{7})^2 – 2\times2\sqrt{5}\times\sqrt{7}}$
= $\sqrt{(\sqrt{7} – 2\sqrt{5})^2}$
= $\pm(\sqrt{7} – 2\sqrt{5})$
13) Answer (B)
let the number be xy
Given x=3y-4
10x+y-(10y+x)=18
9(x-y)=18
x-y=2
3y-4-y=2
2y=6
y=3
Required number is 53
Square root of 53=7.28
14) Answer (B)
15) Answer (A)
we have $(a-b)^{2}$=$a^{2}+b^{2}-2ab$
Comparing this with $214-78\sqrt{5}$ = $a^{2}+b^{2}-2ab$
We have 214=$a^{2}+b^{2}$
& $ab = 39\sqrt{5}$
For a=13 and b=3$\sqrt{5}$; 2ab=2*13*3$\sqrt{5}$
And so required answer is 13-3$\sqrt{5}$
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