In what ratio should a shopkeeper mix Rs.20/kg rice with Rs.28/kg rice so that the selling price of the mixture will become Rs.30/kg, if he sells the rice at 20% profit.

3 : 5

20% = \(\frac{1}{5}\),

C.P. : S.P. = 5 : 6

S.P. of mixture = 6R = 30 (given)

∴ 1R = 5

C.P of mixture = 5R = 5 × 5 = Rs. 25

Now, Using allegation method:

Therefore,

Req. ratio = 3 : 5