A shopkeeper bought 80 kg of rice at a discount of 10%. Besides 1 kg rice was offered free to him on the purchase of every 20 kg rice. If he sells the rice at the marked price, his profit percentage will be:

$16 \frac{2}{3} \%$

Let SP of 1 kg rice = Rs. 1

SP of 80 kg rice = Rs. 80

CP of 80 kg rice = 80 × \(\frac{9}{10}\) = Rs. 72

Rice got free on 80 kg = \(\frac{80}{20}\) = 4 kg

Total quantity of rice = 80 + 4 = 84 kg

Total SP of total rice = 84

Profit = 84 – 72 = 12

∴ Profit percentage = \(\frac{12}{72}\) × 100 = $16 \frac{2}{3} \%$