A man invested some part of Rs. 10,000 in ICICI bank at the rate of 10% interest per annum and rest of the money in SBI bank at the rate of 20% per annum. At the end of the year he received total Rs. 1200 as interest. Find the amount he invested in ICICI bank.

Rs. 8000

Total rate of interest = \(\frac{1200}{10,000}\) × 100 = 12%

By using allegation method:

               ICICI           SBI

Rate:         10%           20%

                         12%      

Principal:     8       :       2

                  4       :       1       ⇒ 5R  →   10,000 (given)

So, invested in ICICI = 4R →   \(\frac{10,000}{5}\) × 4 = 8000