Bunuel
A trader has 60 kg of rice, a part of which he sells at 16% profit and the rest at 8% loss. On the whole loss is 6%. What is the quantity sold at 16% profit ?
(A) 5 kg
(B) 7 kg
(C) 8 kg
(D) 9 kg
(E) 15 kg
Let the cost of one kilogram of rice be c, let the amount sold at 16% profit be x kg.
The x kg of rice were sold at 16% profit, which means the selling price was 1.16c per kg. Thus, the revenue from this part was x * 1.16c.
The rest of the rice, which is 60 - x kg, was sold at 8% loss, which means the selling price was 0.92c per kg. Thus, the revenue from this part was (60 - x) * 0.92c.
In total, the trader earned a revenue of x * 1.16c + (60 - x) * 0.92c.
Since the trader bought 60 kg of rice and paid c per kg, the total cost is 60c. We are told that the trader suffered a loss of 6% in total, which means the trader earned 60c * 0.94 in total. Let's set this amount equal to the expression we obtained earlier:
\(\Rightarrow\) x * 1.16c + (60 - x) * 0.92c = 60c * 0.94
\(\Rightarrow\) c(x * 1.16 + (60 - x) * 0.92) = 60c * 0.94
\(\Rightarrow\) 1.16x + 60 * 0.92 - 0.92x = 0.94 * 60
\(\Rightarrow\) 1.16x - 0.92x = 0.94 * 60 - 0.92 * 60
\(\Rightarrow\) 0.24x = 0.02 * 60
\(\Rightarrow\) 24x = 2 * 60
\(\Rightarrow\) x = 120/24 = 5
We see that 5 kilograms of rice were sold at 16% profit.
Answer: A