Question

A boy buys 9 apples for Rs 9.60 and sells them at 11 for Rs 12. Find his gain or loss percent.

Answer 1

$$\begin{gathered} \mathrm{C}.\mathrm{P}\mathrm{of}9\mathrm{apples}=\mathrm{Rs}9.60 \\ \therefore \mathrm{C}.\mathrm{P}\mathrm{of}1\mathrm{apple}=\mathrm{Rs}\frac{9.60}{9}=\mathrm{Rs}\frac{16}{15} \\ \mathrm{S}.\mathrm{P}\mathrm{of}11\mathrm{apples}=\mathrm{Rs}12 \\ \therefore \mathrm{S}.\mathrm{P}\mathrm{of}1\mathrm{apple}=\mathrm{Rs}\frac{12}{11} \\ \mathrm{Clearly},\mathrm{S}.\mathrm{P}\mathrm{of}1\mathrm{apple}>\mathrm{C}.\mathrm{P}\mathrm{of}1\mathrm{apple} \\ \mathrm{So},\mathrm{we}\mathrm{get}\mathrm{profit}\mathrm{on}\mathrm{selling}\mathrm{apples} \\ \mathrm{Gain}\%=\left(\frac{\mathrm{gain}\times 100}{\mathrm{C}.\mathrm{P}.}\right) \\ =\left(\frac{{\displaystyle \frac{12}{11}}-{\displaystyle \frac{16}{15}}}{{\displaystyle \frac{16}{15}}}\right)\times 100 \\ =\left(\frac{12\times 15-16\times 11}{15\times 11}\right)\times \frac{15}{16}\times 100 \\ =\left(\frac{180-176}{11\times 16}\right)\times 100 \\ =\left(\frac{4}{11\times 16}\right)\times 100 \\ =2\frac{3}{11}\% \end{gathered}$$