Question Detail

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

213414
213424
213434
213444

Answer: Option D

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 = 2 x 2 x 3 x 3 x 7 x 7 x 11 x 11 = 213444

1. \begin{aligned} \sqrt{\frac{32.4}{x}} = 2 \end{aligned}

Answer: Option B

2. Evaluate \begin{aligned} \sqrt[3]{\sqrt{.000064}} \end{aligned}

0.0002
0.002
0.02
0.2

Answer: Option D

Explanation:

\begin{aligned} = \sqrt{.000064} \end{aligned}
\begin{aligned} = \sqrt{\frac{64}{10^6}} \end{aligned}
\begin{aligned} = \frac{8}{10^3} = .008 \end{aligned}
\begin{aligned} = \sqrt[3]{.008} \end{aligned}
\begin{aligned} = \sqrt[3]{\frac{8}{1000}} \end{aligned}
\begin{aligned} = \frac{2}{10} = 0.2 \end{aligned}

3. What is the square root of 0.16

0.4
0.04
0.004
4

Answer: Option A

Explanation:

as .4 * .4 = 0.16

4. What is the smallest number by which 3600 be divided to make it a perfect cube.

Answer: Option A

Explanation:

\begin{aligned}
3600 = 2^3 \times 5^2 \times 3^2 \times 2
\end{aligned}
To make it a perfect cube it must be divided by
\begin{aligned}
5^2 \times 3^2 \times 2 = 450
\end{aligned}

5. if a = 0.1039, then the value of
\begin{aligned} \sqrt{4a^2 - 4a + 1} + 3a \end{aligned}

12.039
1.2039
11.039
1.1039

Answer: Option D

Explanation:

Tip: Please check the question carefully before answering. As 3a is not under the root we can convert it into a formula , lets evaluate now :

\begin{aligned}
= \sqrt{4a^2 - 4a + 1} + 3a \end{aligned}

\begin{aligned}
= \sqrt{(1)^2 + (2a)^2 - 2x1x2a} + 3a \end{aligned}

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

\begin{aligned}
= (1-2a) + 3a \end{aligned}

\begin{aligned}
= (1-2a) + 3a \end{aligned}

\begin{aligned}
= 1 + a = 1 + 0.1039 = 1.1039 \end{aligned}