A shopkeeper purchases 11 knives in ₹ 10 and sells them at the rate of 10 knives for ₹ 11. He earns a profit… · ABC26GN2665

Suppose, number of knives bought = L.C.M. of 11 and $10=110$. $$\begin{aligned} & \text { C.P. of } 110 \text { knives }=₹\left(\frac{10}{11} \times 110\right)=₹ 100 . \\ & \text { S.P. of } 110 \text { knives }=₹\left(\frac{11}{10} \times 110\right)=₹ 121 . \\ & \therefore \text { Profit } \%=\left(\frac{21}{100} \times 100\right) \%=21 \% . \end{aligned}$$