Alligation or Mixture problems
Some amount out of Rs. 7000 was lent at 6 % p.a. and the remaining at 4 % p. a. If the total simple interest from both the fractions in 5 years was Rs. 1600, the sum lent at 6 % p. a. was ?
By the rule of alligation: Cost of 1 kg pulses of 1st kind Cost of 1 kg pulses of 2nd kind Rs. 15 Mean Price Rs. 16.50 Rs. 20 3.50 1.50 ∴ Required rate = 3.50 : 1.50 = 7 : 3.
By the rule of alligation, we have: Strength of first jar Strength of 2nd jar 40% MeanStrength 26% 19% 7 14 So, ratio of 1st and 2nd quantities = 7 : 14 = 1 : 2 ∴ Required quantity replaced = 2 3