Question 4

Explanation

First, we calculate the total capital (buying price) for $100$ durians.

Next, we calculate the total revenue from sales. The sales are divided into two parts: the first $70$ fruits and the remaining $30$ fruits.

Revenue from the first 70 fruits:

Revenue from the remaining 30 fruits:

Thus, the total revenue is:

Since the total revenue is greater than the total capital, the dealer makes a profit. The profit amount is the difference between revenue and capital:

Finally, we calculate the profit percentage relative to the initial capital:

So, the dealer makes a profit of $13.75\%$.