# Decimal Numbers Quiz Set 014

### Question 1

What is \${5.32^2 - 5.65^2}/{5.32 - 5.65}\$?

A

10.97.

B

+0.33.

C

-10.97.

D

-.33.

Soln.
Ans: a

We know \$a^2 - b^2\$ = \$(a - b) × (a + b)\$. So \${a^2 - b^2}/{a - b}\$ is same as a + b. We get a + b = 5.32 + 5.65 = 10.97.

### Question 2

What is y in \$7.907 + 0.7 + y = 0.06\$?

A

-8.547.

B

+8.547.

C

-7.547.

D

+7.547.

Soln.
Ans: a

y = 0.06 - (0.7 + 7.907) = -8.547.

### Question 3

664945 is same as?

A

\$6.64945 × 10^{5}\$.

B

\$6.64945 × 10^{4}\$.

C

\$6.64945 × 10^{6}\$.

D

\$6.64945 × 10^{3}\$.

Soln.
Ans: a

### Question 4

What is \${3.39^3 - 0.20^3}/{3.39^2 + 0.678 + 0.20^2}\$?

A

3.19.

B

4.19.

C

5.19.

D

2.19.

Soln.
Ans: a

We know \${a^3 - b^3}/{a^2 + ab + b^2}\$ is same as \${(a - b) × (a^2 + ab + b^2)}/{a^2 + ab + b^2}\$ which is same as a - b. So we get a - b = 3.39 - 0.20 = 3.19.

### Question 5

What is \${42 × 1.9 - 68 × 5.2}/9.1\$?

A

\$-30{8/91}\$.

B

\$-30{7/91}\$.

C

\$-30{6/91}\$.

D

\$-30{9/91}\$.

Soln.
Ans: a

Observe that all fractional numbers are having one digit to the right of the dot. So we can cancel all the dots and get a plain expression: \${42 × 19 - 68 × 52}/91\$ which equals \${-2738/91}\$, which is same as: \$-30{8/91}\$ 