Question

A milkman cheats his customers by adding water to the milk he sells. He starts the day with 1000 litres of milk. However, after selling every 500 litres of milk, he adds an equal quantity of water to what he already has. The milkman can get away by cheating as long as the milk to water ratio does not fall below 1 : 7. Each customer brings exactly 2 litres of milk a day (except for the first 100 who buy 5 litres each). The total number of customers the milkman has cheated if he ends up selling all the milk is :

Answer 1

1000lM=100 customers buy 5l each=500lM
Rest 500lM+500lW=1000l
Ration=1:1
Rest 500l=250lW+250lM
500l+500l(W)=250l(W)+500l(W)+250(M)
Ration=1:3
Rest 500l=125l(M)+375l(W)
adding 500l water
1000(l)=125l(M)+875l(W)
Ratio=1:7
Total cheated customers=500+250+250
=1000 customers were cheated.