Question

Sundaram buys 40 kg of wheat at Rs 6.25 per kg and 30 kg of wheat at Rs 7 per kg. At what rate per kg should he sell the mixture to gain 5% on the whole?

Answer 1

CP of the first variety of wheat = Rs $40\times 6.25=\mathrm{Rs}.250$
CP of second variety of wheat = Rs $30\times 7=Rs\mathit{.}210$
Total CP = Rs (250 + 210)
= Rs 460
Total amount of wheat = (40 + 30) kg
= 70 kg
$$\begin{gathered} \mathrm{Now},\mathrm{gain}\mathrm{percentage}=\frac{\mathrm{gain}}{\mathrm{CP}}\times 100 \\ \Rightarrow \mathrm{Gain}=\frac{(\mathrm{gain}\%)\times \mathrm{CP}}{100} \\ \Rightarrow \mathrm{Gain}=\frac{460\times 5}{100} \\ =\mathrm{Rs}23 \\ \therefore \mathrm{SP}=\mathrm{CP}+\mathrm{gain} \\ =460+23 \\ =\mathrm{Rs}483 \end{gathered}$$

∴ Rate per kg = Rs $\frac{483}{70}=Rs6.9$