A shopkeeper mixed 10 kg of rice costing Rs. 10 per kg with a certain quantity of another variety of rice costing Rs. 15 per kg. He sold the mixture at the rate of Rs. 14 per kg. What was the quantity of the second variety of rice, if he gained by 5 %?
Let the quantity of second
verity of rice =x kg
Then C.P. of the next mixture = 10×10+15×x= Rs. (100+15x)
S.P. of the mixture = (10+x)× Rs. 14= Rs. (140+14x)
Gain=(140+14x)−(100+15x)=40−x
According to the
question
∴ Gain %= (40−x100+15x)×100=5
⇒ 4000−100x=500+75x
⇒ 175x=3500
⇒x=3500175=20 kg