- Vijay invested Rs.50,000 partly at 10% and partly at 15%. His total
income after a year was Rs.7000. How much did he invest at the rate of 10%?
(1) Rs.40,000 (2) Rs.40,000 (3) Rs.12,000 (4) Rs.20,000
Solution:
The best way to solve this problem is by using the concept in
Mixtures and Alligation.
Vijay earned a total income of Rs.7000 for his investment of 50,000.
Therefore, his average rate of return =
By rule of alligation, if the value of one of the products is 10 (cheaper) and
the other is 15 (dearer) and if the two are mixed such that the average value of
the mixture is 14 (mean price), then the two products have been mixed in the
following ratio.
The ratio of
-
Cheaper product : Dearer product
(Dearer product price - mean price) : (Mean price - cheaper product price)
Therefore, the amount invested @10% interest = (1/5) * 50,000= 10,000.
