In what ratio should a shopkeeper mix two types of rice, one costing ₹20 per kg and another costing ₹40 per kg to get a rice variety costing ₹28 per kg?

3 : 2

The correct answer is Option (2) → 3 : 2

$\text{Let the two types of rice cost }20\text{ and }40\text{ per kg.}$

$\text{Mean price }=28$

$\text{Use alligation: }$

$40-28=12,\quad 28-20=8$

$\text{Required ratio}=12:8$

$=\;3:2$

The rice must be mixed in the ratio $3:2$.