Answer: The merchant made a profit of Rs 35,000 by selling the potatoes.
Explanation:
To find the profit or loss of the merchant, we first need to calculate the revenue he earned from selling the potatoes.
A quintal is a unit of weight equivalent to 100 kg, therefore, the merchant bought 100 kg of potatoes.
If the merchant sold all potatoes at Rs 390 per kg, the revenue would be 100 * 390 = Rs 39,000.
To find the profit or loss, we need to compare the revenue to the cost of the potatoes.
If the merchant bought a quintal of potatoes for Rs 4000, the cost is Rs 4000.
To calculate the profit or loss, we can use the following formula:
Profit or loss = Revenue - Cost
Using this formula, we can calculate the profit or loss as:
Profit or loss = 39,000 - 4,000 = Rs 35,000
So, the merchant made a profit of Rs 35,000 by selling the potatoes.
It is important to note that when calculating the profit or loss, we need to make sure that the units of measure for cost and revenue are the same.