A shopkeeper has 300 Kg millet, a part of which he sells at 10% profit. The remaining quantity of millet was of poor quality, and he sold it at a 5% loss. In the whole transaction, he made a profit of 7%. The quantity of the millet sold at 5% loss is:

60 Kg

The correct answer is Option (2) → 60 Kg

Let $x$ kg be sold at $5\%$ loss.

Then $(300-x)$ kg is sold at $10\%$ profit.

Assume cost price per kg $=100$.

Total cost price:

$300\times100=30000$

Overall profit $7\%$ gives total selling price:

$30000\times1.07=32100$

Selling price of $(300-x)$ kg at $10\%$ profit:

$(300-x)\times110$

Selling price of $x$ kg at $5\%$ loss:

$x\times95$

Equation:

$(300-x)\times110+x\times95=32100$

$33000-110x+95x=32100$

$33000-15x=32100$

$15x=900$

$x=60$

final answer: $60$ kg