Milk costs ₹60 a litre. In what ratio must water be mixed with the milk so that the mixture costs ₹45 a litre?

Explanation

1. 01

   Water is the cheaper kind, at ₹0. Water : milk $= (60 - 45) : (45 - 0) = 15 : 45$.

2. 02

   In lowest terms, 1 : 3.