### 3. A certain sum is invested for 2 years in scheme M at 20% p.a. compound interest (compounded annually), Same sum is also invested for the same period in scheme N at k% p.a. simple interest. The interest earned from scheme M is twice of that earned from scheme N. What is the value of k?

### 4. Find the compound interest on Rs. 6,500 for 4 years if the rate of interest is 10% p.a. for the first 2 years and 20% per annum for the next 2 years?

### 5. What is the interest rate per annum, if a sum of money invested at compound interest amount to Rs. 2400 in 3 years and in 4 years to Rs. 2,520?

### 6. A sum is equally invested in two different schemes on CI at the rate of 15% and 20% for two years. If interest gained from the sum invested at 20% is Rs. 528.75 more than the sum invested at 15%, find the total sum?