A shopkeeper bought 20 kg of sugar at Rs. 45 per kg, 25 kg of sugar at Rs. 50 per kg and 35 kg of sugar at Rs. 40 per kg. He spent a sum of Rs. 450 on transportation and other expense. He mixed all 3 types of sugar and sold all the stock at Rs. 54.5 per kg. His profit percent was:

9%

Cost price:

⇒ 20 kg at Rs. 45 per kg = 20 × 45 = 900

⇒ 25 kg at Rs. 50 per kg = 25 × 50 = 1250

⇒ 35 kg at Rs. 40 per kg = 35 × 40 = 1400

Total C.P. = 900 + 1250 + 1400 + 450* = 4000

(*Rs.450 is transportation and other expense)

C.P. per kg = \(\frac{4000}{80}\) = Rs. 50

S.P. per kg = Rs. 54.5

Profit per kg = 4.50

Profit percent = \(\frac{4.5}{50}\) × 100% = 9%