Simple and Compound Interest

A man earns x% on the first Rs. 2,000 and y% on the rest of his income. If he earns Rs. 700 from income of Rs. 4,000 and Rs. 900 from if his income is Rs. 5,000, find x%.

1. 10%
2. 15%
3. 20%
4. 25%

How much time will it take for an amount of Rs. 450 to yield Rs. 81 as interest at 4.5% per annum of simple interest?

1. 4 years
2. 4.5 years
3. 5 years
4. 5.5 years

A certain sum of money invested at some rate of simple interest triple itself in 4 years. In how many years the principal will become 9 times of itself at the same rate?

A man invests Rs. 3,000 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?

1. Rs. 1,200
2. Rs. 1,500
3. Rs. 1,700
4. Rs. 2,000