Exercise: 2-A
Find the product:
Q1: \frac{5}{6} \times \frac{3}{7}
Step 1:
Write the multiplication of two fractions:
\frac{5}{6} \times \frac{3}{7}
Multiply the numerators and the denominators: = \frac{5\times3}{6\times7} = \frac{15}{42}
Simplify the fraction by dividing numerator and denominator by 3: = \frac{15\div3}{42\div3} = \frac{5}{14}
Q2: \frac{7}{18} \times \frac{9}{14}
Step 1:
Write the multiplication of two fractions:
\frac{7}{18} \times \frac{9}{14}
Multiply the numerators and the denominators: = \frac{7\times9}{18\times14} = \frac{63}{252}
Simplify the fraction by dividing numerator and denominator by 9: = \frac{63\div9}{252\div9} = \frac{7}{28}
Simplify further by dividing by 7: = \frac{7\div7}{28\div7} = \frac{1}{4}
Q3: 28 \times \frac{7}{8}
Step 1:
Write the multiplication:
28 \times \frac{7}{8}
Convert 28 into fraction form: = \frac{28}{1} \times \frac{7}{8}
Multiply the numerators and denominators: = \frac{28\times7}{1\times8} = \frac{196}{8}
Simplify by dividing numerator and denominator by 4: = \frac{196\div4}{8\div4} = \frac{49}{2}
Convert into mixed fraction: = 24\frac{1}{2}
Q4: 7 \times \frac{1}{7}
Step 1:
Write the multiplication:
7 \times \frac{1}{7}
Multiply numerator and denominator: = \frac{7\times1}{7} = \frac{7}{7}
Simplify: = 1
Q5: 2\frac{1}{25} \times \frac{5}{17}
Step 1:
Convert mixed fraction to improper fraction:
2\frac{1}{25} = \frac{(2\times25)+1}{25} = \frac{51}{25}
Multiply the two fractions: \frac{51}{25} \times \frac{5}{17}
Multiply numerators and denominators: = \frac{51\times5}{25\times17} = \frac{255}{425}
Simplify the fraction by dividing by 85: = \frac{255\div85}{425\div85} = \frac{3}{5}
Q6: 1\frac{1}{13} \times 7\frac{3}{7}
Step 1:
Convert mixed fractions to improper fractions:
1\frac{1}{13} = \frac{14}{13}, \quad 7\frac{3}{7} = \frac{52}{7}
Multiply the two fractions: \frac{14}{13} \times \frac{52}{7}
Multiply numerators and denominators: = \frac{14\times52}{13\times7} = \frac{728}{91}
Convert into mixed fraction:
Divide 728 by 91: 728 \div 91 = 8 \text{ remainder } 0
Q7: \frac{4}{17} \times 7\frac{1}{12}
Step 1:
First, convert the mixed number into an improper fraction:
7\frac{1}{12} = \frac{7\times12 + 1}{12} = \frac{85}{12}
Now, multiply the two fractions: \frac{4}{17} \times \frac{85}{12}
Multiply the numerators and denominators: = \frac{4\times85}{17\times12} = \frac{340}{204}
Simplify the fraction:
Divide numerator and denominator by 68: = \frac{5}{3}
Convert to mixed fraction if needed: \frac{5}{3} = 1\frac{2}{3}
Q8: 7\frac{1}{4} \times \frac{7}{58} \times 1\frac{11}{21}
Step 1:
Convert mixed fractions to improper fractions:
7\frac{1}{4} = \frac{29}{4}, \quad 1\frac{11}{21} = \frac{32}{21}
Multiply all three fractions: \frac{29}{4} \times \frac{7}{58} \times \frac{32}{21}
Simplify before multiplying:
29 and 58 have common factor 29: = \frac{1}{2}
Multiply numerators and denominators: = \frac{1\times7\times32}{4\times2\times21} = \frac{224}{168}
Simplify by dividing by 56: = \frac{224\div56}{168\div56} = \frac{4}{3}
Convert into mixed fraction: = 1\frac{1}{3}
Q9: \frac{1}{19} \times 91 \times 5\frac{11}{13}
Step 1:
Convert mixed fraction to improper fraction:
5\frac{11}{13} = \frac{76}{13}
Multiply all numbers:
First simplify \frac{1}{19} \times 91: \frac{1}{19} \times 91 = \frac{91}{19} = 4\frac{15}{19}
Now multiply: 4\frac{15}{19} \times \frac{76}{13}
Thus, \frac{91}{19} \times \frac{76}{13} = \frac{91\times76}{19\times13} = \frac{6916}{247}
Convert to mixed fraction: 6916 \div 247 = 28 \text{ remainder } 0
Q10: 7\frac{1}{4} \times 2\frac{3}{16} \times 2\frac{2}{7}
Step 1:
Convert mixed fractions to improper fractions:
7\frac{1}{4} = \frac{29}{4}, \quad 2\frac{3}{16} = \frac{35}{16}, \quad 2\frac{2}{7} = \frac{16}{7}
Multiply all three fractions: \frac{29}{4} \times \frac{35}{16} \times \frac{16}{7}
Simplify before multiplying:
16 cancels with 16: = \frac{29}{4} \times \frac{35}{7}
Convert into mixed fraction: = 36\frac{1}{4}
Q11: Find the value of:
(i) \frac{3}{4} of \frac{8}{9} = \frac{3}{4} \times \frac{8}{9} = \frac{24}{36} = \frac{2}{3}
(ii) \frac{1}{2} of 2\frac{2}{3}
Convert 2\frac{2}{3} = \frac{8}{3} = \frac{1}{2} \times \frac{8}{3} = \frac{8}{6} = \frac{4}{3} = 1\frac{1}{3}
(iii) \frac{4}{5} of 1 hour
= \frac{4}{5} \times 60\ \text{minutes} = 48\ \text{minutes}
(iv) \frac{3}{5} of ₹1
= \frac{3}{5} \times 1 = ₹0.60
(v) \frac{8}{15} of 1\frac{1}{2} metres
Convert 1\frac{1}{2} = \frac{3}{2} = \frac{8}{15} \times \frac{3}{2} = \frac{24}{30} = \frac{4}{5}
(vi) \frac{5}{7} of 2\frac{1}{3} kg
Convert 2\frac{1}{3} = \frac{7}{3} = \frac{5}{7} \times \frac{7}{3} = \frac{5}{3} = 1\frac{2}{3}
Q12: A car can travel 12\frac{1}{2} km in 1 litre of petrol. How much distance can it travel in 42\frac{3}{5} litres of petrol?
Step 1:
Convert mixed numbers into improper fractions:
12\frac{1}{2} = \frac{25}{2}, \quad 42\frac{3}{5} = \frac{213}{5}
Multiply distance per litre by the number of litres: \text{Distance} = \frac{25}{2} \times \frac{213}{5}
Multiply numerators and denominators: = \frac{25\times213}{2\times5} = \frac{5325}{10}
Simplify: = 532.5\ \text{km}
Q13: A graphic designer charges ₹27\frac{3}{5} for each diagram. Pind the amount he will charge if he designs 186 diagrams for a book.
Step 1:
Convert mixed fraction to improper fraction:
27\frac{3}{5} = \frac{138}{5}
Multiply charge per diagram with number of diagrams: \text{Total Amount} = \frac{138}{5} \times 186
Multiply: = \frac{138\times186}{5} = \frac{25668}{5}
Divide: = 5133.6 = 5133\frac{3}{5}
Q14: If a cloth costs ₹715\frac{1}{4} per metre, find the cost of 3\frac{2}{5} metres of this cloth.
Step 1:
Convert mixed numbers into improper fractions:
715\frac{1}{4} = \frac{2861}{4}, \quad 3\frac{2}{5} = \frac{17}{5}
Multiply cost per metre by number of metres: \text{Total Cost} = \frac{2861}{4} \times \frac{17}{5}
Multiply numerators and denominators: = \frac{2861\times17}{4\times5} = \frac{48637}{20}
Simplify: = 2431\frac{17}{20} = 2431.85
Q15: Advertising in a magazine costs ₹1472\frac{2}{5} per square inch. Find the cost of an advertisement of 17\frac{6}{7} square inch.
Step 1:
Convert mixed numbers into improper fractions:
1472\frac{2}{5} = \frac{7362}{5}, \quad 17\frac{6}{7} = \frac{125}{7}
Multiply cost per square inch with area in square inches: \text{Total Cost} = \frac{7362}{5} \times \frac{125}{7}
Multiply numerators and denominators: = \frac{7362\times125}{5\times7} = \frac{920250}{35}
Simplify: = 26292\frac{6}{7} = 26292.8571
Q16: A car from city A to city B with a uniform speed of 52\frac{2}{7} km per hour. Find the distance between the two cities, if it took 4\frac{3}{8} hours for the car to reach city B from city A.
Step 1:
Convert mixed numbers into improper fractions:
52\frac{2}{7} = \frac{366}{7}, \quad 4\frac{3}{8} = \frac{35}{8}
Multiply speed and time: \text{Distance} = \frac{366}{7} \times \frac{35}{8}
Simplify before multiplying: \frac{35}{7} = 5,\quad \text{thus}
Simplify: = 228\frac{3}{4} = 228.75\ \text{km}
Q17: The length of a rectangular plot of land is 29\frac{3}{7} m. If its breadth is 12\frac{8}{11} m, find its area.
Step 1:
Convert mixed numbers into improper fractions:
29\frac{3}{7} = \frac{206}{7}, \quad 12\frac{8}{11} = \frac{140}{11}
Area of rectangle = Length × Breadth: \text{Area} = \frac{206}{7} \times \frac{140}{11}
Multiply numerators and denominators: = \frac{206\times140}{7\times11} = \frac{28840}{77}
Simplify: = 374\frac{6}{11} = 374.4156\ \text{m}^2