Class 7 Percentage Exercise 11.4

\begin{array}{l} \text {Q1. Find each of the following: } \\ \text {(i) } \quad 7 \% \text { of Rs. } 7150 \\ \text {(ii) } \quad 40 \% \text { of } 400 \text { kg } \\ \text {(iii) } \quad 20 \% \text { of } 15.125 \text { litres } \\ \text {(iv) } \quad 3 \frac{1}{3} \% \text { of }90 \text { km } \\ \text {(v) } \quad 2.5 \% \text { of }600 \text { metres } \end{array}\begin{array}{l} \text {Sol. } \\ \text {(i) } \quad 7 \% \text { of Rs. } 7150 =(\frac{7}{100} \times 7150) \\ =\text {Rs. }500.50 \\ \\\text {(ii) } \quad 40 \% \text { of } 400 \text { kg } =(\frac{40}{100} \times 400) =160 \text { kg } \\ \\\text {(iii) } \quad 20 \% \text { of } 15.125 \text { litres } =(\frac{20}{100} \times 15.125) =3.025 \text { litres } \\ \\\text {(iv) } \quad 3 \frac{1}{3} \% \text { of }90 \text { km } = (\frac{10}{300} \times 90) =3 \text { km } \\ \\\text {(v) } \quad 2.5 \% \text { of }600 \text { metres } =(\frac{2.5}{100} \times 600) =15 \text { metres }\end{array}\begin{array}{l} \text {Q2. Find the number whose } 12 \frac{1}{2} \% \text { is 64 } \end{array}\begin{array}{l} \text {Sol. } \\ \text {Let’s assume that the required number be x.} \\ \text {Then, } 12 \frac{1}{2} \% \times x=64 \\ \Rightarrow \quad \frac{25}{2} \% \times x=64 \\ \Rightarrow \quad \frac{25}{2 \times 100} \times x=64 \\ \Rightarrow \quad x= \frac{2 \times 100}{25} \times 64 \\ \Rightarrow \quad x= 8 \times 64 = 512 \\\therefore \text {The required number is 512.}\end{array}\begin{array}{l} \text {Q3. What is the number, } 6 \frac{1}{4} \% \text { of which is 2 ? } \end{array}\begin{array}{l} \text {Sol. } \\ \text {Let’s assume that the required number be x.} \\ \text {Then, } 6 \frac{1}{4} \% \times x=2 \\ \Rightarrow \quad \frac{25}{4} \% \times x=2 \\ \Rightarrow \quad \frac{25}{4 \times 100} \times x=2 \\ \Rightarrow \quad x= \frac{4 \times 100}{25} \times 2 \\ \Rightarrow \quad x= 16 \times 2 = 32 \\\therefore \text {The required number is 32.}\end{array}\begin{array}{l} \text {Q4. If 6 is } 50 \% \text { of a number, what is that number? }\end{array}\begin{array}{l} \text {Sol. } \\ \text {Let’s assume that the required number be x.} \\ \text {Then, } 50 \% \times x=6 \\ \Rightarrow \quad \frac{50}{100} \times x=6 \\ \Rightarrow \quad x= \frac{100}{50} \times 6 \\ \Rightarrow \quad x= 2 \times 6 = 12 \\\therefore \text {The required number is 12.}\end{array}