Practice MCQ Questions and Answer on Decimal Fraction

71.

The value of $$\frac{3.6\times 0.48\times 2.50}{0.12\times 0.09\times 0.5}$$    is :

• (A) 80
• (B) 800
• (C) 8000
• (D) 80000

Show Answer

 $$\eqalign{ & = \frac{{3.6 \times 0.48 \times 2.50}}{{0.12 \times 0.09 \times 0.5}} \cr & = \frac{{36 \times 48 \times 250}}{{12 \times 9 \times 5}} \cr & = 800 \cr} $$

72.

0.04 x 0.0162 is equal to:

• (A) 6.48 x 10-3
• (B) 6.48 x 10-4
• (C) 6.48 x 10-5
• (D) 6.48 x 10-6

Show Answer

 4 x 162 = 648. Sum of decimal places = 6. So, 0.04 x 0.0162 = 0.000648 = 6.48 x 10-4

73.

What is the difference between the biggest and the smallest fraction among $$\frac{2}{3}$$, $$\frac{3}{4}$$, $$\frac{4}{5}$$ and $$\frac{5}{6}$$ ?

• (A) $$\frac{1}{6}$$
• (B) $$\frac{1}{12}$$
• (C) $$\frac{1}{20}$$
• (D) $$\frac{1}{30}$$

Show Answer

 Converting each of the given fractions into decimal form, we get : $$\frac{2}{3}$$ = 0.66 $$\frac{3}{4}$$ = 0.75 $$\frac{4}{5}$$ = 0.8 $$\frac{5}{6}$$ = 0.833 Since 0.833 > 0.8 > 0.75 > 0.66 So, $$\frac{5}{6}$$ > $$\frac{4}{5}$$ > $$\frac{3}{4}$$ > $$\frac{2}{3}$$ ∴ Required difference = $$\left( {\frac{5}{6} - \frac{2}{3}} \right) = \frac{1}{6}$$

74.

47.7 × 12.4 × 8.6 = ?

• (A) 5086.728
• (B) 5218.668
• (C) 5708.428
• (D) 6180.656

Show Answer

 477 × 124 × 86 = 5086728 Sum of decimal place = 3 ∴ 47.7 × 12.4 × 8.6 = 5086.728

75.

Solve : $${\left(\frac{0.05}{0.25}+\frac{0.25}{0.05}\right)}^3=?$$

• (A) 139.4
• (B) 140
• (C) 140.6
• (D) 143.6

Show Answer

 $$\eqalign{ & {\left( {\frac{{0.05}}{{0.25}} + \frac{{0.25}}{{0.05}}} \right)^3} \cr & = {\left( {\frac{5}{{25}} + \frac{{25}}{5}} \right)^3} \cr & = {\left( {\frac{1}{5} + 5} \right)^3} \cr & = {\left( {\frac{{26}}{5}} \right)^3} \cr & = {\left( {5.2} \right)^3} \cr & = 140.608 \approx 140.6 \cr} $$

76.

The value of $$\frac{{\left(0.06\right)}^2+{\left(0.47\right)}^2+{\left(0.079\right)}^2}{{\left(0.006\right)}^2+{\left(0.047\right)}^2+{\left(0.0079\right)}^2}$$       is :

• (A) 0.1
• (B) 10
• (C) 100
• (D) 1000

Show Answer

 Given expression : $$ = \frac{{{a^2} + {b^2} + {c^2}}}{{{{\left( {\frac{a}{{10}}} \right)}^2} + {{\left( {\frac{b}{{10}}} \right)}^2} + {{\left( {\frac{c}{{10}}} \right)}^2}}}$$ Where a = 0.06, b = 0.47 and c = 0.079 $$\eqalign{ & = \frac{{100\left( {{a^2} + {b^2} + {c^2}} \right)}}{{\left( {{a^2} + {b^2} + {c^2}} \right)}} \cr & = 100 \cr} $$

77.

The least among the following is:

• (A) 0.2
• (B) 1 ÷ 0.2
• (C) $$0.\bar{2}$$
• (D) (0.2)2

Show Answer

 $$\eqalign{ & 1 \div 0.2 = \frac{1}{{0.2}} = \frac{{10}}{2} = 5; \cr & 0.\overline 2 = 0.222...; \cr & {\left( {0.2} \right)^2} = 0.04 \cr & 0.04 0.2 0.22.... 5 \cr & {\text{Since}}\,0.04\,{\text{is}}\,{\text{the}}\,{\text{least,}}\,{\text{so}}\,{\left( {0.2} \right)^2}\,{\text{is}}\,{\text{the}}\,{\text{least}}. \cr} $$

78.

Express $$\frac{1999}{2111}$$ in decimal :

• (A) 0.893
• (B) 0.904
• (C) 0.946
• (D) 0.986

Show Answer

 $$\therefore \frac{{1999}}{{2111}} = 0.946$$

79.

The correct expression of $$6.\overline{46}$$ in the fractional form is:

• (A) $$\frac{646}{99}$$
• (B) $$\frac{64640}{1000}$$
• (C) $$\frac{640}{100}$$
• (D) $$\frac{640}{99}$$

Show Answer

 $$\eqalign{ & 6.\overline {46} \cr & = 6 + 0.\overline {46} \cr & = 6 + \frac{{46}}{{99}} \cr & = \frac{{594 + 46}}{{99}} \cr & = \frac{{640}}{{99}} \cr} $$

80.

The value of (1.25)³ - 2.25 (1.25)² + 3.75 (0.75)² - (0.75)³ is :

• (A) 1
• (B) $$\frac{1}{2}$$
• (C) $$\frac{1}{4}$$
• (D) $$\frac{1}{8}$$

Show Answer

 Given expression : (1.25)3 - (0.75)3 - 3 × (1.25)2 × 0.75 + 3 × 1.25 × (0.75)2 = (1.25 - 0.75)3 = (0.5)3 = $${\left( {\frac{1}{2}} \right)^3}$$ = $$\frac{1}{8}$$ [∵ (a - b)3 = a3 - b3 - 3a2 b + 3ab2]