In what ratio must a grocer mix two varieties of tea worth Rs. 60 a kg and Rs. 65 a kg so that by selling the mixture at Rs. 68.20 a kg he may gain 10%?

A. 3 : 2 B. 3 : 4 C. 3 : 5 D. 4 : 5Answer: Option A
S.P. of 1 kg of the mixture = Rs. 68.20, Gain = 10% C.P. of 1 kg of the mixture = Rs. $\left(\frac{100}{110} \times 68.20\right)$ = Rs. 62 BY the rule of alligation, we have: ∴ Required ratio = 3 : 2