Square and Cube Roots Quiz Set 005

Question 1

What is the value of \$x\$ in \$√{0.0064 × x}\$ = 0.8?

A

100.

B

8.

C

80.

D

0.8.

Soln.
Ans: a

The given expression can be simplified to \$0.0064 × x\$ = \$0.8^2\$, which gives x = \${0.8^2}/0.0064\$, which is same as \$0.64/0.0064\$ which gives 100.

Question 2

What is the value of \$(√2 - 1/√2)^2\$?

A

\${1/2}\$.

B

\${1/4}\$.

C

\${2/3}\$.

D

\${2/5}\$.

Soln.
Ans: a

I will give a general solution for any n. \$(√n - 1/√n)^2\$ is same as \$({(√n)^2 - 1}/√n)^2\$ which becomes \$(n - 1)^2/n\$. Putting n = 2, we get \${1/2}\$.

Question 3

How many 4 digit numbers are their whose squares end in 2?

A

0.

B

4.

C

10.

D

21.

Soln.
Ans: a

It is not possible for the square of any number to end in 2, 3, 7 or 8. Hence the answer is 0.

Question 4

What is the value of \$√{3 + √36}\$?

A

3.

B

9.

C

4.

D

6.

Soln.
Ans: a

The given expression is same as \$√{3 + √6^2}\$, which becomes \$√{3 + 6}\$, or \$√9\$ which gives 3 as the answer. Please note that squares of as many numbers should be always on your tips.

Question 5

Each canvas of a group of canvases has as many dots as is the total number of canvases in that group of canvases. If there are 25 dots in all, how many canvases are there?

A

5.

B

√5.

C

25.

D

16.

Soln.
Ans: a

Let the number of canvases = n. So dots in one canvas are also n, and therefore, dots in n canvases = \$n^2\$. We have been given \$n^2 = 25\$, which gives n = 5.