Square Root and Cube Root

Question:
The cube root of .000216 is:

[A].

.6

[B].

.06

[C].

77

[D].

87

Answer: Option B

Explanation:

(.000216)1/3	=		216		1/3
			106

=		6 x 6 x 6		1/3
		102 x 102 x 102

=	6
	102

=	6
	100

   = 0.06

Question:
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:

[A].

57

[B].

67

[C].

77

[D].

87

Answer: Option C

Explanation:

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

Number of members = 5929 = 77.

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

[A].

213444

[B].

214344

[C].

214434

[D].

231444

Answer: Option A

Explanation:

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

Question:
If a = 0.1039, then the value of 4a2 – 4a + 1 + 3a is:
[A].

0.1039

[B].

0.2078

[C].

1.1039

[D].

2.1039

Answer: Option C

Explanation:

4a2 – 4a + 1 + 3a
= (1)2 + (2a)2 – 2 x 1 x 2a + 3a

   = (1 – 2a)2 + 3a

   = (1 – 2a) + 3a

   = (1 + a)

   = (1 + 0.1039)

   = 1.1039

Question:
The square root of (7 + 35) (7 – 35) is
[A].

5

[B].

2

[C].

4

[D].

35

Answer: Option B

Explanation:

(7 + 35)(7 – 35)

=

(7)2 – (35)2

= 49 – 45  = 4  = 2.

Question:
If 35 + 125 = 17.88, then what will be the value of 80 + 65 ?
[A].

13.41

[B].

20.46

[C].

21.66

[D].

22.35

Answer: Option D

Explanation:

35 + 125 = 17.88

35 + 25 x 5 = 17.88

35 + 55 = 17.88

85 = 17.88

5 = 2.235

80 + 65 = 16 x 5 + 65

   = 45 + 65

   = 105 = (10 x 2.235) = 22.35

Question:
0.0169 x ? = 1.3
[A].

10

[B].

100

[C].

1000

[D].

None of these

Answer: Option B

Explanation:

Let 0.0169 x x = 1.3.

Then, 0.0169x = (1.3)2 = 1.69

x =	1.69	= 100
	0.0169

Question: 1.5625 = ?
[A].

1.05

[B].

1.25

[C].

1.45

[D].

1.55

Answer: Option B

Explanation:

1|1.5625( 1.25
|1
|——-
22| 56
| 44
|——-
245| 1225
| 1225
|——-
| X
|——-

1.5625 = 1.25.

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

[A].

1

[B].

2

[C].

3

[D].

None of these

Answer: Option D

Explanation:

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

Question:
The square root of 64009 is:

[A].

253

[B].

347

[C].

363

[D].

803

Answer: Option A

Explanation:

2|64009( 253
|4
|———-
45|240
|225
|———-
503| 1509
| 1509
|———-
| X
|———-

64009 = 253.