Mandar bought a calculator and sold it to Ketan at a profit of 5%. Ketan sold it to Tushar at a loss of 25%. If Tushar paid Rs. 3780, then the cost price (in Rs. ) of the calculator Mandar bought is

Correct option is A

Given:
Profit by Mandar = 5%
Loss by Ketan = 25%
Final Selling Price = Rs. 3780
Formula Used:
​$$\text{Selling Price}=\text{Cost Price}\times\left(1\pm\frac{\text{Profit/Loss}\%}{100}\right)$$​​
Solution:
Ketan sold the calculator to Tushar at 25% loss:
​$$3780 = \text{CP}_{\text{Ketan}} \times \frac{75}{100}\\\ \\\text{CP}_{\text{Ketan}} = \frac{3780 \times 100}{75} = 5040$$​​
Mandar sold the calculator to Ketan at 5% profit:

$$5040 = \text{CP}_{\text{Mandar}} \times \frac{105}{100}\\\ \\\text{CP}_{\text{Mandar}} = \frac{5040 \times 100}{105} = 4800$$​​

Cost Price of the calculator Mandar bought = Rs. 4800