# Decimal Numbers Quiz Set 008

### Question 1

What is \${31 × 8.8 - 27 × 3.2}/4.2\$?

A

\$44{8/21}\$.

B

\$44{5/21}\$.

C

\$44{1/21}\$.

D

\$44{11/21}\$.

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: \${31 × 88 - 27 × 32}/42\$ which equals \${932/21}\$, which is same as: \$44{8/21}\$

### Question 2

For what value of x would this expression be a perfect square: \$6.39 × 6.39 + x × 6.39 + 0.5 × 0.5\$?

A

1.

B

10.

C

0.1.

D

0.01.

Soln.
Ans: a

Comparing the given expression with \$a^2 + 2 × a ×b + b^2 = (a + b)^2\$, we see that if a = 6.39, and b = 0.5 then by inspection, x should be equal to 2b = 2 × 0.5 = 1.

### Question 3

What is x in \$0.001/x = 0.1\$?

A

0.01.

B

0.1.

C

1.0.

D

0.001.

Soln.
Ans: a

The expression becomes \$x = {1/1000} × {10}\$ = 0.01.

### Question 4

If \$7.06/0.9\$ = 7.844444, then \$0.0706/9\$ = ?

A

0.007844444.

B

0.07844444.

C

0.7844444.

D

7.844444.

Soln.
Ans: a

Numerator is divided by 100, and denominator multiplied by 10, so the answer should get divided by 1000.

### Question 5

What is x in \${437/0.0437} = {4.37/x}\$?

A

\$4.37 × 10^{-4}\$.

B

\$4.37 × 10^{-3}\$.

C

\$4.37 × 10^{-2}\$.

D

\$4.37 × 10^{-5}\$.

Soln.
Ans: a
Transposing, x = \$4.37 × {0.0437/437}\$ which gives 0.000437, which, in scientific form is \$4.37 × 10^{-4}\$. 