Decimal Numbers Quiz Set 011


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Question 1

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.


Question 2

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 3

What is x in $0.0098/x = 0.098$?

 A

0.1.

 B

0.01.

 C

1.0.

 D

0.001.

Soln.
Ans: a

The expression becomes $x = {98/98} × {1000/10000}$ = 0.1.


Question 4

What is ${0.50 × 0.50 × 0.50 + 0.06 × 0.06 × 0.06}/{4.50 × 4.50 × 4.50 + 0.54 × 0.54 × 0.54}$?

 A

$1/9^3$.

 B

$1/9^2$.

 C

$1/9^4$.

 D

$1/9$.

Soln.
Ans: a

By inspection, the given ratio is same as ${0.50 × 0.50 × 0.50 + 0.06 × 0.06 × 0.06}/{9^3 × ({0.50 × 0.50 × 0.50 + 0.06 × 0.06 × 0.06})}$ which is $1/9^3$.


Question 5

What is ${2.50^2 - 2.26^2}/{2.50 - 2.26}$?

 A

+4.76.

 B

0.024.

 C

0.24.

 D

-4.76.

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 = 2.50 + 2.26 = 4.76.


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This Blog Post/Article "Decimal Numbers Quiz Set 011" by Parveen (Hoven) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Updated on 2020-02-07. Published on: 2016-04-21

Posted by Parveen(Hoven),
Aptitude Trainer


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