A person having bought goods for Rs.400 sells half of it at a gain of 5%. At what gain percentage must he sell the remainder, so as to gain 25% on the whole?

30% 25% 20% 45%

45%

Let the quantity = 4 then the overall SP must be = 4 × 125%= 5 Half is sold at 5% profit means = 2 × 105% = 2.1 Now half must be sold at = 5 - 2.1 = 2.9 Gain on half = 2.9- 2 = 0.9 Gain percentage =  \(\frac{0.9 × 100 }{2}\) = 45%