In what ratio should a variety of rice costing Rs. 7 per kg be mixed with another variety of rice costing Rs. 8.75 per kg to obtain a mixture costing Rs. 7.50 per kg? Options.
A) 5 / 6  B) 5 / 2  C) 5 / 1  D) 5 / 3  E) 7 / 6

Rationale: "let us say the ratio of the quantities of cheaper and dearer varieties = x : y by the rule of allegation , x / y = ( 8.75 - 7.50 ) / ( 7.50 - 7 ) = 5 / 2 answer : b"
Answer: B