Amar Singh started a business with an initial investment of ₹400000. In the first year, he incurred a loss of 4%. However, during the second year, he earned a profit of 5% which in third year rose to 10%. Calculate his net profit for the entire period of 3 years.

Given,

Investment = ₹400000

Loss in first year = 4%,

Profit in second year = 5%,

Profit in third year = 10%.

$\therefore \text{Amt. after 3 yrs.} = ₹400000\Big(1 - \dfrac{4}{100}\Big)\Big(1 + \dfrac{5}{100}\Big)\Big(1 + \dfrac{10}{100}\Big) \\[1em] = ₹400000 \times \dfrac{96}{100} \times \dfrac{105}{100} \times \dfrac{110}{100} \\[1em] = ₹400000 \times \dfrac{24}{25} \times \dfrac{21}{20} \times \dfrac{11}{10} \\[1em] = ₹400000 \times \dfrac{5544}{5000} \\[1em] = ₹(80 \times 5544) \\[1em] = ₹443520.$

Net profit = Amount - Principal = ₹443520 - ₹400000 = ₹43520.

Hence, net profit after 3 years = ₹43520.