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Quantitative Aptitude

SQUARE ROOT AND CUBE ROOT MCQs

Square Roots, Cube Roots, Squares And Square Roots

Total Questions : 547 | Page 11 of 55 pages
Question 101. The lengths 18 cm, 24 cm and 30 cm form the sides of a right-angled triangle.
  1.    True
  2.    False
  3.    125
  4.    150
 Discuss Question
Answer: Option A. -> True
:
A
182+242=324+576=900=302
Since the squares of 18 and 24 add up to the square of 30, the numbers 18, 24 and 30form a Pythagorean triplet, and hence, can be used to represent the three sides of a right- angled triangle.
Question 102. Use Prime Factorization method to find the square root of the following:-  
i. (1024)   =   ______
 ii. (2025)   =  _______
  1.    32, 45
  2.    36, 35
  3.    28, 25
  4.    28, 45
 Discuss Question
Answer: Option A. -> 32, 45
:
A
1024=2×2×2×2×2×2×2×2×2×2
=22×22×22×22×22(1024)=(22×22×22×22×22)=2×2×2×2×2=32
2025=3×3×3×3×5×5
=32×32×52(2025)=(32×32×52)=3×3×5=45
Question 103. Find the square root of 3364 by Long division Method.
  1.    58
  2.    68
  3.    78
  4.    88
 Discuss Question
Answer: Option A. -> 58
:
A
Given number: 3364
By grouping the numbers from theleft, we get¯¯¯¯¯¯33¯¯¯¯¯¯64.
Now, perform the long division.
585¯¯¯¯¯¯33¯¯¯¯¯¯64251088648640
Thus, the square root of 3364 is 58.
Question 104. 1,024 trees are planted in a grid fashion such that the number of rows is equal to the number of columns. One row and one column of trees are cut such that the number of rows and columns after cutting remain equal. Find the number of trees that were cut?
  1.    61
  2.    63
  3.    65
  4.    67
 Discuss Question
Answer: Option B. -> 63
:
B
Number of trees = 1024. Since number of rows = number of columns, this means that the number of trees is a perfect square. Therefore number of rows/columns = square root of 1024 (number of trees).
1024= 2×2×2×2×2×2×2×2×2×2=32
Therefore, the initial number of rows/columns = 32. After cutting 1 row and one column, number of rows/columns = 32-1 = 31.
The remaining number of trees = 312.
Therefore, number of trees that were cut = 322312 = 1024 - 961 = 63.
Question 105. How many non-perfect squares lie in between 752 and 762 ?
  1.    75
  2.    100
  3.    125
  4.    150
 Discuss Question
Answer: Option D. -> 150
:
D
Between the squares of any two consecutive numbers n and (n+1), lie 2n non-perfect squares.
Therefore between squares of 75 and 76 (n = 75 and n + 1 = 76), lie (2 x 75) = 150 non-perfect squares.
Question 106. Three identical square sheets of paper need to be cut into 4, 5, and 6 stripes of equal size respectively. Find the minimum length of the side of the original square sheet.
Three Identical Square Sheets Of Paper Need To Be Cut Into 4...
  1.    45
  2.    40
  3.    30
  4.    25
 Discuss Question
Answer: Option C. -> 30
:
C
Since the square sheet needs to be divided equally into 4, 5, and 6 equal parts respectively, its area must be a perfect square divisible by 4, 5, and 6; or the area of the square sheet should be a multiple of 4, 5, and 6.
L. C. M. of 4, 5, and 6 = 60. But 60 is not a perfect square.
60=2×2×3×5=22×3×5.
If we multiply the LCM by 3 and 5 both, it will become a perfect square. Therefore the minimum area of the square sheet =60×3×5=900 sq. units.
Now 900 is a minimum perfect square, which is divisible by 4, 5, and 6. Therefore the side of the square should be the square root of the area of the square (Area of a square = side2 sq. units).
Hence, the minimum length of the side of the square = (900)=(22×32×52) = 30 units.
Question 107. If 2=1.4142, then the square of 14.142 should approximately be?
  1.    20
  2.    200
  3.    2000
  4.    2500
 Discuss Question
Answer: Option B. -> 200
:
B
2=1.4142 (Given)
Multiply both sides by 10
10×2=14.142
100×2=14.142
Squaringboth sides, we get thesquare of 14.142 to be approximately equal to 200.
Question 108. In general, if a natural number m can be expressed as n2, where n is also a natural number, then m is a __________.
  1.    perfect square
  2.    perfect  cube
  3.    perfect number
  4.    irrational number
 Discuss Question
Answer: Option A. -> perfect square
:
A
If m can be expressed as n2, where n is a natural number then, m is called a perfect square.
Question 109. Find the square of 39.
  1.    78
  2.    1500
  3.    1521
  4.    1530
 Discuss Question
Answer: Option C. -> 1521
:
C
The number 39 ends with 9.And92=81which ends with 1.Hence,392should have 1 in the unitsplace.
We can observefrom options thatonly 1521 satisfies this.Hence 1521 is the answer.
Alternatively, 39 should be multipliedwith 39 to obtain the square.
So,39×39=1521.
Question 110. Numbers like 1, 4, 9, 16, 25, ... are known as ________.
  1.    Perfect cubes
  2.    Perfect squares
  3.    Irrational Numbers
  4.    Decimals
 Discuss Question
Answer: Option B. -> Perfect squares
:
B
When an integer is multiplied by itself, it results in a perfect square.
When we square integers like 1, 2, 3, 4, 5, ...,we obtain 1, 4, 9, 16, 25, ... .
Hence, the given numbers which are obtained by squaring the integers are known as perfect squares.

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