# Decimal Numbers Quiz Set 019

### Question 1

What is \$8.958 - (-0.4) + 0.05 - (-0.08)\$?

A

9.488.

B

8.999.

C

8.975.

D

8.488.

Soln.
Ans: a

The given expression is same as \$8.958 + 0.4 + 0.05 + 0.08\$, then by simple addition we get \$8.958 + 0.4 + 0.05 + 0.08 = 9.488\$.

### Question 2

What is \${4.42^2 - 4.05^2}/{4.42 - 4.05}\$?

A

8.47.

B

7.47.

C

6.47.

D

9.47.

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 = 4.42 + 4.05 = 8.47.

### Question 3

What is \${88 × 6.6 - 68 × 6.3}/1.3\$?

A

\$117{3/13}\$.

B

\$117{1/13}\$.

C

\$117{5/13}\$.

D

\$117{7/13}\$.

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: \${88 × 66 - 68 × 63}/13\$ which equals \${1524/13}\$, which is same as: \$117{3/13}\$

### Question 4

What is \${5.05^2 - 4.75^2}/{5.05 - 4.75}\$?

A

9.80.

B

8.90.

C

10.20.

D

8.49.

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 = 5.05 + 4.75 = 9.80.

### Question 5

For what value of x would this expression be a perfect square: \$4.2 × 4.2 - x × 4.2 + 0.4 × 0.4\$?

A

0.8.

B

0.08.

C

0.008.

D

8.0.

Soln.
Ans: a

Comparing the given expression with \$a^2 - 2 × a ×b + b^2 = (a - b)^2\$, we see that if a = 4.2, and b = 0.4 then by inspection, x should be equal to 2b = 2 × 0.4 = 0.8.

This Blog Post/Article "Decimal Numbers Quiz Set 019" by Parveen (Hoven) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Updated on 2017-05-17.

Posted by Parveen(Hoven),
Aptitude Trainer