In what ratio must a person mix three kinds of tea costing Rs.60/kg, Rs.75/kg and Rs.100 /kg so that the resultant mixture when sold at Rs.96/kg yields a profit of 20%?

1. 1 : 2 : 4
2. 3 : 7 : 6
3. 1 : 4 : 2
4. None of these

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