1]A dairy man pays Rs.6.4 per litre of milk.He adds water and sells the mixture at Rs.8 per litre,thereby making 37.5% profit.The proportion of water to milk recieved by the customers is
a]10:1 b]10:2 c]10:3 d]10:4

required ratio of the water and the milk in the mixture = x:y
CP of x litres of milk = Rs.6.4 x
SP of x litres of milk = Rs. 8(x+y)
profit % = 37.5
gaint % =( sp/cp *100) - 100
37.5 = [{8(x+y) } /64.x ]* 100 - 100
137.5/100 = (8x + 8y )/6.4x
880x - 800x = 800y
80x = 800 y
x/y = 10:1