# Decimal Numbers Quiz Set 001

### Question 1

What is \${8.00^3 - 0.90^3}/{8.00^2 + 7.200 + 0.90^2}\$?

A

7.10.

B

6.95.

C

7.56.

D

6.56.

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 = 8.00 - 0.90 = 7.10.

### Question 2

For what value of x would this expression be a perfect square: \$9.74 × 9.74 + x × 9.74 + 0.3 × 0.3\$?

A

0.6.

B

0.06.

C

0.006.

D

6.0.

Soln.
Ans: a

Comparing the given expression with \$a^2 + 2 × a ×b + b^2 = (a + b)^2\$, we see that if a = 9.74, and b = 0.3 then by inspection, x should be equal to 2b = 2 × 0.3 = 0.6.

### Question 3

What is \$5.06 + 0.9 + 0.09\$?

A

6.05.

B

5.05.

C

6.95.

D

5.95.

Soln.
Ans: a

By simple addition we get \$5.06 + 0.9 + 0.09 = 6.05\$.

### Question 4

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 5

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.