Lakshya Education MCQs

Question:

By what least number 675 be multiplied to  obtain a number which is a perfect cube ?

Options:
A.4
B.5
C.6
D.7
Answer: Option B

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More Questions on This Topic :

Question 1.

Evaluate     \(\sqrt[3]{\sqrt{0.000064}}\)  = ?

Options:
  1.    0.2
  2.    0.02
  3.    0.002
  4.    0.0002
Answer: Option A
Question 2.

  1. A General wishes to draw up his 36581 soldiers in the form of a solid square. After arranging them , he found that some of them are left over . How many are left ?

Options:
  1.    90
  2.    100
  3.    110
  4.    120
Answer: Option B
Question 3.

If  \(If 5 + 2√3 = a + b√3 , then find the value of a and b .\)  =   a +  b√3   , then find the value of  a and b .

Options:
  1.    a = – 6 ,  b = – 11 
  2.    a = – 11 ,  b = – 6
  3.    a = – 6 ,  b = 11 
  4.    a = 11 ,  b = – 6
Answer: Option D
Question 4.

The cube root of .000216 is:

Options:
  1.    .6
  2.    .06
  3.    77
  4.    87
Answer: Option B

(.000216)1/3 = \(\left(\frac{216}{10^{6}}\right)^{\frac{1}{3}}\)

= \(\left(\frac{6\times6\times6}{10^{2}\times10^{2}\times10^{2}}\right)^{\frac{1}{3}}\)

=\(\frac{6}{10^{2}}\)

= \(\frac{6}{100}\)

=0.06

Question 5.

What should come in place of both x in the equation \(\frac{x}{128} = \frac{162}{x}.\)

Options:
  1.    12
  2.    14
  3.    144
  4.    196
Answer: Option A

\(Let\frac{x}{128} = \frac{162}{x}\)

Then x2 = 128 x 162

   = 64 x 2 x 18 x 9

   = 82 x 62 x 32

= 8 x 6 x 3

   = 144.

Therefore  x = 144 = 12.

 

 

 

Question 6.

The least perfect square, which is divisible by each of 21, 36 and 66 is:

Options:
  1.    213444
  2.    214344
  3.    214434
  4.    231444
Answer: Option A

L.C.M. of 21, 36, 66 = 2772.

Now, 2772 = 2 x 2 x 3 x 3 x 7 x 11

To make it a perfect square, it must be multiplied by 7 x 11.

So, required number = 22 x 32 x 72 x 112 = 213444