The mean daily profit by a shopkeeper in a month of 30 days was ₹450. If the mean profit for the first 20 days was ₹300, then the mean profit for the last 10 days will be:

Correct option is A

​Given:
Mean daily profit for 30 days = ₹450
Mean daily profit for the first 20 days = ₹300
Number of days in the month = 30
Formula Used:
​$$\text{Mean Profit} = \frac{\text{Total Profit}}{\text{Number of Days}}$$​​
Solution:
Total Profit for 30 days = 450 $$\times$$​ 30 = ₹13,500
Total Profit for 20 days = 300 $$\times$$ 20 = ₹6,000
Total Profit for the last 10 days = Total Profit for 30 days - Total Profit for 20 days = ₹13,500 - ₹6,000 = ₹7,500
Mean Profit for the last 10 days = $$\frac {₹7,500}{ 10} = ₹750$$​​
Thus, the mean profit for the last 10 days is ₹750.