How much interest will be received in 2.5 years at the rate of 4 percent simple interest of Rs. 3,680?

The strength of a school increases and decreases in every alternate year by 10 %. It started with increase in 2000, then the strength of the school in 2003 as compared to that in 2000 was : 

16 men can complete a piece of work in 7 days. In how many days will 28 men complete the same work?

Some amount out of Rs.7000 was lent at 6% per annum and the remaining at 4% per annum. If the total simple interest from both the fractions in 5 year was Rs.1600, find the sum lent at 6% per annum.

Suresh is half his father’s age. After 20 years, his father’s age will be one and a half times Suresh’s age. What is his father’s age now?

What are the roots of the quadratic equations?

  $$(x^2 + 3x - 154 = 0)$$

What will come in place of the question mark (?) in each of the following series?

3 22 ? 673 2696 8093