10. A sum of Rs. 41 was divided among 50 boys and girls. Each boy gets 90 paise and a girl 65 paise. The number of boys is ?

11. In what proportion must wheat at Rs. 1.60 per kg. be mixed with wheat at Rs. 1.45 per kg., so that the mixture be worth Rs. 1.54 per kg. ?

12. The ratio of milk and water in 66 kg. of adulterated milk is 5 : 1. Water is added to it to make the ratio 5 : 3. The quantity of water added is :