A man invests Rs. 6,000 at the rate of 5% per annum. How much more should he invest at the rate of 8%, so that he can earn a total of 6% per annum?  Choose the correct answer.
A) Rs. 1200  B) Rs. 1300  C) Rs. 1500  D) Rs. 3000  E) None of these
Explanation :   Interest on Rs.6000 at 5% per annum = ( 6000 × 5 × 1) / 100 = Rs. 300   Let his additional investment at 8% = x   Interest on Rs.x at 8% per annum = ( x × 8 × 1 ) / 100 = 2x/25.   To earn 6% per annum for the total, interest = (6000 + x) × 6 × 1/100.   =&gt; 300 + 2x/25 = (6000 + x) × 6 × 1/100.   =&gt; 30000 + 8x = (6000 + x) × 6.   =&gt; 30000 + 8x = 36000 + 6x.   =&gt; 2x=6000.   =&gt; x=3000.   Answer : Rs. 3000
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A man invests Rs. 6,000 at the rate of 5% per annum. How much more should he invest at the rate of 8%, so that he can earn a total of 6% per annum?