Exercise: 2-A
Find the product:
Q1: \(\frac{5}{6} \times \frac{3}{7}\)
Step 1:
Write the multiplication of two fractions:
\[
\frac{5}{6} \times \frac{3}{7}
\]
Step 2:
Multiply the numerators and the denominators:
\[
= \frac{5\times3}{6\times7}
= \frac{15}{42}
\]
Step 3:
Simplify the fraction by dividing numerator and denominator by 3:
\[
= \frac{15\div3}{42\div3}
= \frac{5}{14}
\]
Answer: \(\frac{5}{14}\)
Q2: \(\frac{7}{18} \times \frac{9}{14}\)
Step 1:
Write the multiplication of two fractions:
\[
\frac{7}{18} \times \frac{9}{14}
\]
Step 2:
Multiply the numerators and the denominators:
\[
= \frac{7\times9}{18\times14}
= \frac{63}{252}
\]
Step 3:
Simplify the fraction by dividing numerator and denominator by 9:
\[
= \frac{63\div9}{252\div9}
= \frac{7}{28}
\]Step 4:
Simplify further by dividing by 7:
\[
= \frac{7\div7}{28\div7}
= \frac{1}{4}
\]Answer: \(\frac{1}{4}\)
Q3: \(28 \times \frac{7}{8}\)
Step 1:
Write the multiplication:
\[
28 \times \frac{7}{8}
\]Step 2:
Convert 28 into fraction form:
\[
= \frac{28}{1} \times \frac{7}{8}
\]Step 3:
Multiply the numerators and denominators:
\[
= \frac{28\times7}{1\times8}
= \frac{196}{8}
\]Step 4:
Simplify by dividing numerator and denominator by 4:
\[
= \frac{196\div4}{8\div4}
= \frac{49}{2}
\]Step 5:
Convert into mixed fraction:
\[
= 24\frac{1}{2}
\]Answer: \(24\frac{1}{2}\)
Q4: \(7 \times \frac{1}{7}\)
Step 1:
Write the multiplication:
\[
7 \times \frac{1}{7}
\]Step 2:
Multiply numerator and denominator:
\[
= \frac{7\times1}{7}
= \frac{7}{7}
\]Step 3:
Simplify:
\[
= 1
\]Answer: \(1\)
Q5: \(2\frac{1}{25} \times \frac{5}{17}\)
Step 1:
Convert mixed fraction to improper fraction:
\[
2\frac{1}{25} = \frac{(2\times25)+1}{25} = \frac{51}{25}
\]Step 2:
Multiply the two fractions:
\[
\frac{51}{25} \times \frac{5}{17}
\]Step 3:
Multiply numerators and denominators:
\[
= \frac{51\times5}{25\times17}
= \frac{255}{425}
\]Step 4:
Simplify the fraction by dividing by 85:
\[
= \frac{255\div85}{425\div85}
= \frac{3}{5}
\]Answer: \(\frac{3}{5}\)
Q6: \(1\frac{1}{13} \times 7\frac{3}{7}\)
Step 1:
Convert mixed fractions to improper fractions:
\[
1\frac{1}{13} = \frac{14}{13}, \quad 7\frac{3}{7} = \frac{52}{7}
\]Step 2:
Multiply the two fractions:
\[
\frac{14}{13} \times \frac{52}{7}
\]Step 3:
Multiply numerators and denominators:
\[
= \frac{14\times52}{13\times7}
= \frac{728}{91}
\]Step 4:
Convert into mixed fraction:
Divide 728 by 91:
\[
728 \div 91 = 8 \text{ remainder } 0
\]
So,
\[
= 8
\]Answer: \(8\)
Q7: \(\frac{4}{17} \times 7\frac{1}{12}\)
Step 1:
First, convert the mixed number into an improper fraction:
\[
7\frac{1}{12} = \frac{7\times12 + 1}{12} = \frac{85}{12}
\]Step 2:
Now, multiply the two fractions:
\[
\frac{4}{17} \times \frac{85}{12}
\]Step 3:
Multiply the numerators and denominators:
\[
= \frac{4\times85}{17\times12}
= \frac{340}{204}
\]Step 4:
Simplify the fraction:
Divide numerator and denominator by 68:
\[
= \frac{5}{3}
\]Step 5:
Convert to mixed fraction if needed:
\[
\frac{5}{3} = 1\frac{2}{3}
\]Answer: \(1\frac{2}{3}\)
Q8: \(7\frac{1}{4} \times \frac{7}{58} \times 1\frac{11}{21}\)
Step 1:
Convert mixed fractions to improper fractions:
\[
7\frac{1}{4} = \frac{29}{4}, \quad 1\frac{11}{21} = \frac{32}{21}
\]Step 2:
Multiply all three fractions:
\[
\frac{29}{4} \times \frac{7}{58} \times \frac{32}{21}
\]Step 3:
Simplify before multiplying:
\(29\) and \(58\) have common factor 29:
\[
= \frac{1}{2}
\]
Thus,
\[
\frac{1}{4} \times \frac{7}{2} \times \frac{32}{21}
\]Step 4:
Multiply numerators and denominators:
\[
= \frac{1\times7\times32}{4\times2\times21}
= \frac{224}{168}
\]Step 5:
Simplify by dividing by 56:
\[
= \frac{224\div56}{168\div56}
= \frac{4}{3}
\]Step 6:
Convert into mixed fraction:
\[
= 1\frac{1}{3}
\]Answer: \(1\frac{1}{3}\)
Q9: \(\frac{1}{19} \times 91 \times 5\frac{11}{13}\)
Step 1:
Convert mixed fraction to improper fraction:
\[
5\frac{11}{13} = \frac{76}{13}
\]Step 2:
Multiply all numbers:
First simplify \(\frac{1}{19} \times 91\):
\[
\frac{1}{19} \times 91 = \frac{91}{19} = 4\frac{15}{19}
\]Step 3:
Now multiply:
\[
4\frac{15}{19} \times \frac{76}{13}
\]Convert \(4\frac{15}{19}\) into improper fraction:
\[
= \frac{(4\times19)+15}{19} = \frac{91}{19}
\]Step 4:
Thus,
\[
\frac{91}{19} \times \frac{76}{13}
= \frac{91\times76}{19\times13}
= \frac{6916}{247}
\]Step 5:
Convert to mixed fraction:
\[
6916 \div 247 = 28 \text{ remainder } 0
\]
Thus,
\[
= 28
\]Answer: \(28\)
Q10: \(7\frac{1}{4} \times 2\frac{3}{16} \times 2\frac{2}{7}\)
Step 1:
Convert mixed fractions to improper fractions:
\[
7\frac{1}{4} = \frac{29}{4}, \quad 2\frac{3}{16} = \frac{35}{16}, \quad 2\frac{2}{7} = \frac{16}{7}
\]Step 2:
Multiply all three fractions:
\[
\frac{29}{4} \times \frac{35}{16} \times \frac{16}{7}
\]Step 3:
Simplify before multiplying:
\(16\) cancels with \(16\):
\[
= \frac{29}{4} \times \frac{35}{7}
\]Now, \(35\div7 = 5\):
\[
= \frac{29}{4} \times 5
= \frac{145}{4}
\]Step 4:
Convert into mixed fraction:
\[
= 36\frac{1}{4}
\]Answer: \(36\frac{1}{4}\)
Q11: Find the value of:
(i) \(\frac{3}{4}\) of \(\frac{8}{9}\)
\[
= \frac{3}{4} \times \frac{8}{9}
= \frac{24}{36}
= \frac{2}{3}
\]Answer = \(\frac{2}{3}\)
(ii) \(\frac{1}{2}\) of \(2\frac{2}{3}\)
Convert \(2\frac{2}{3} = \frac{8}{3}\)
\[
= \frac{1}{2} \times \frac{8}{3}
= \frac{8}{6}
= \frac{4}{3}
= 1\frac{1}{3}
\]Answer = \(1\frac{1}{3}\)
(iii) \(\frac{4}{5}\) of 1 hour
\[
= \frac{4}{5} \times 60\ \text{minutes}
= 48\ \text{minutes}
\]Answer = \(48\) minutes
(iv) \(\frac{3}{5}\) of ₹1
\[
= \frac{3}{5} \times 1
= ₹0.60
\]Answer = ₹0.60
(v) \(\frac{8}{15}\) of \(1\frac{1}{2}\) metres
Convert \(1\frac{1}{2} = \frac{3}{2}\)
\[
= \frac{8}{15} \times \frac{3}{2}
= \frac{24}{30}
= \frac{4}{5}
\]Answer = \(\frac{4}{5}\) metres = 80 cm
(vi) \(\frac{5}{7}\) of \(2\frac{1}{3}\) kg
Convert \(2\frac{1}{3} = \frac{7}{3}\)
\[
= \frac{5}{7} \times \frac{7}{3}
= \frac{5}{3}
= 1\frac{2}{3}
\]Answer = \(1\frac{2}{3}\) kg
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:
\[
12\frac{1}{2} = \frac{25}{2}, \quad 42\frac{3}{5} = \frac{213}{5}
\]Step 2:
Multiply distance per litre by the number of litres:
\[
\text{Distance} = \frac{25}{2} \times \frac{213}{5}
\]Step 3:
Multiply numerators and denominators:
\[
= \frac{25\times213}{2\times5}
= \frac{5325}{10}
\]Step 4:
Simplify:
\[
= 532.5\ \text{km}
\]Answer: \(532.5\) 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:
\[
27\frac{3}{5} = \frac{138}{5}
\]Step 2:
Multiply charge per diagram with number of diagrams:
\[
\text{Total Amount} = \frac{138}{5} \times 186
\]Step 3:
Multiply:
\[
= \frac{138\times186}{5}
= \frac{25668}{5}
\]Step 4:
Divide:
\[
= 5133.6 = 5133\frac{3}{5}
\]Answer: ₹5133.60 or ₹\(5133\frac{3}{5}\)
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:
\[
715\frac{1}{4} = \frac{2861}{4}, \quad 3\frac{2}{5} = \frac{17}{5}
\]Step 2:
Multiply cost per metre by number of metres:
\[
\text{Total Cost} = \frac{2861}{4} \times \frac{17}{5}
\]Step 3:
Multiply numerators and denominators:
\[
= \frac{2861\times17}{4\times5}
= \frac{48637}{20}
\]Step 4:
Simplify:
\[
= 2431\frac{17}{20} = 2431.85
\]Answer: ₹\(2431\frac{17}{20}\) or ₹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:
\[
1472\frac{2}{5} = \frac{7362}{5}, \quad 17\frac{6}{7} = \frac{125}{7}
\]Step 2:
Multiply cost per square inch with area in square inches:
\[
\text{Total Cost} = \frac{7362}{5} \times \frac{125}{7}
\]Step 3:
Multiply numerators and denominators:
\[
= \frac{7362\times125}{5\times7}
= \frac{920250}{35}
\]Step 4:
Simplify:
\[
= 26292\frac{6}{7} = 26292.8571
\]Answer: ₹\(26292\frac{6}{7}\) or ₹26292.86
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:
\[
52\frac{2}{7} = \frac{366}{7}, \quad 4\frac{3}{8} = \frac{35}{8}
\]Step 2:
Multiply speed and time:
\[
\text{Distance} = \frac{366}{7} \times \frac{35}{8}
\]Step 3:
Simplify before multiplying:
\[
\frac{35}{7} = 5,\quad \text{thus}
\]
\[
\text{Distance} = \frac{366\times5}{8}
= \frac{1830}{8}
\]Step 4:
Simplify:
\[
= 228\frac{3}{4} = 228.75\ \text{km}
\]Answer: \(228\frac{3}{4}\) km or 228.75 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:
\[
29\frac{3}{7} = \frac{206}{7}, \quad 12\frac{8}{11} = \frac{140}{11}
\]Step 2:
Area of rectangle = Length × Breadth:
\[
\text{Area} = \frac{206}{7} \times \frac{140}{11}
\]Step 3:
Multiply numerators and denominators:
\[
= \frac{206\times140}{7\times11}
= \frac{28840}{77}
\]Step 4:
Simplify:
\[
= 374\frac{6}{11} = 374.4156\ \text{m}^2
\]Answer: = \(374\frac{6}{11}\ m^2\) or \(374.42\ m^2\)