Question

IF 12 BOYS EARNS Rs 840 IN 7 DAYS, WHAT WILL 15 BOYS EARN IN 6 DAYS ? HOW CAN WE DO THIS QUESTION BY USING THE DIRECT AND INVERSE PROPORTION RULE i.e. x X_IY₁=X₂Y₂ AND X₁/Y₁= X₂Y₂

Answer 1

$$\begin{gathered} \mathbf{Given}\mathbf{:}\mathbf{}12\mathrm{boys}\mathrm{earn}840\mathrm{rs}\mathrm{in}7\mathrm{days}, \\ \mathrm{then}\mathrm{earning}\mathrm{of}15\mathrm{boys}\mathrm{will}\mathrm{be},\mathrm{by}\mathrm{inversely}\mathrm{proportional}\mathrm{rule}. \\ \mathrm{a}:\mathrm{b}=\mathrm{c}:\mathrm{d} \\ \frac{\mathrm{a}}{\mathrm{b}}=\frac{\mathrm{c}}{\mathrm{d}} \\ \frac{12}{840}=\frac{15}{\mathrm{x}} \\ \mathrm{x}=\frac{15\times 840}{12} \\ \mathrm{x}=1050\mathrm{rs} \\ \mathrm{If}1050\mathrm{earning}\mathrm{is}\mathrm{in}7\mathrm{days}\mathrm{then}6\mathrm{days}\mathrm{earning}\mathrm{will}\mathrm{be} \\ \mathrm{by}\mathrm{inversely}\mathrm{proportional}\mathrm{rule}, \\ \mathrm{p}:\mathrm{q}=\mathrm{r}:\mathrm{s} \\ \frac{\mathrm{p}}{\mathrm{q}}=\frac{\mathrm{r}}{\mathrm{s}} \\ \frac{7}{1050}=\frac{6}{\mathrm{s}} \\ \mathrm{s}=\frac{6\times 1050}{7} \\ \mathbf{}\mathbf{}\mathbf{s}\mathbf{=}\mathbf{}\mathbf{900}\mathbf{}\mathbf{rs}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{}\mathbf{Ans}\mathbf{}\mathbf{} \end{gathered}$$