A man purchased some fruits for Rs. 1000. He sold few fruits worth 400 at 10% profit. At what profit per cent, must he sell the rest in order to gain 20% on the whole?

To get 20% profit on whole,
1000(CP) ⇒ 20%(gain) ⇒ 1200(SP)
Total Profit = 1200 - 1000 = Rs. 200
400 ⇒ 10%(gain) ⇒ 440
He gets Rs. 40 profit on 400
Rest Profit = 200 - 40 = 160
Then he must get Rs. 160 as profit on Rs. 600
Hence, % profit
= $$\frac{{160 \times 100}}{{600}}$$
= $$\frac{{80}}{3}$$
= $$26\frac{2}{3}$$%