Find the ratio in which rice at Rs.7.00 a kg be mixed with rice at Rs.5.70 a kg to produce a mixture worth Rs.6.30 a kg?  Choose the correct choice from the following options
A) 1 : 3 B) 2 : 3 C) 3 : 4 D) 6 : 7 E) none of these

Rationale: "solution required ratio = 60 : 70 = 6 : 7 answer d"
Answer: D