1. **State the problem:** We need to find the median number of customers in the store during the flash sale from the data set: 168, 157, 143, 168, 150, 140, 148, 148, 140, 150. 2. **Recall the formula and rules for median:** The median is the middle value of a data set when the numbers are arranged in ascending order. If the number of data points $n$ is odd, the median is the value at position $\frac{n+1}{2}$. If $n$ is even, the median is the average of the values at positions $\frac{n}{2}$ and $\frac{n}{2}+1$. 3. **Arrange the data in ascending order:** $$140, 140, 143, 148, 148, 150, 150, 157, 168, 168$$ 4. **Determine the number of data points:** There are $n=10$ data points, which is even. 5. **Find the middle positions:** For even $n=10$, the median is the average of the values at positions $\frac{10}{2} = 5$ and $\frac{10}{2} + 1 = 6$. 6. **Identify the values at these positions:** - Value at position 5 is 148 - Value at position 6 is 150 7. **Calculate the median:** $$\text{Median} = \frac{148 + 150}{2} = \frac{298}{2} = 149$$ **Final answer:** The median number of customers during the flash sale is **149**.