Square and Cube Roots Quiz Set 006

Question 1

Each box of a almirah has as many balls as is the total number of boxes in that almirah. If there are 144 balls in all, how many boxes are there?

A

12.

B

9.

C

16.

D

10.

Soln.
Ans: a

Let the number of boxes = n. So balls in one box are also n, and therefore, balls in n boxes = \$n^2\$. We have been given \$n^2 = 144\$, which gives n = 12.

Question 2

What is the value of \$x\$ in \$√{0.0016 × x}\$ = 0.4?

A

100.

B

10.

C

1.

D

1000.

Soln.
Ans: a

The given expression can be simplified to \$0.0016 × x\$ = \$0.4^2\$, which gives x = \${0.4^2}/0.0016\$, which is same as \$0.16/0.0016\$ which gives 100.

Question 3

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

A

0.

B

2.

C

3.

D

4.

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

If \$4√5 + √80 = 17.89\$, then what is the value of \$√125 + 6√5\$?

A

24.60.

B

12.25.

C

25.

D

12.96.

Soln.
Ans: a

The given expression can be rearranged like this: \$4√5 + √{4^{2} × 5}\$, which is same as \$4√5 + 4√5\$ which is same as \$8√5 = 17.89\$, from which we get \$√5 = 2.24\$. Next we can see that \$√125 + 6√5\$ is same as \$√{5^{2} × 5} + 6√5\$, which is same as \$11√5\$, which gives \$11 × 2.24\$ = 24.60.

Question 5

If \$5√3 + √108 = 19.05\$, then what is the value of \$√27 + 3√3\$?

A

10.39.

B

10.64.

C

10.172.

D

10.81.

Soln.
Ans: a

The given expression can be rearranged like this: \$5√3 + √{6^{2} × 3}\$, which is same as \$5√3 + 6√3\$ which is same as \$11√3 = 19.05\$, from which we get \$√3 = 1.73\$. Next we can see that \$√27 + 3√3\$ is same as \$√{3^{2} × 3} + 3√3\$, which is same as \$6√3\$, which gives \$6 × 1.73\$ = 10.39.