Decimal Numbers Quiz Set 019

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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.


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Creative Commons License
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


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