Quantitative Aptitude - Arithmetic Ability Questions

The interest earned on Rs. 1600 at the rate of 5% S>I per annum for 6 yrs would be:

A and B together can do a piece of work in 9 days. If A does thrice the work of B in a given time, the time A alone will take to finish the work is

Rajeev sells a machine for Rs 55 lakhs at a loss. Had he sold it for Rs 67 lakh, his gain would have been 5 times the former loss. Find the cost price of the machine.

The sum of the ages of brother and sister at present is 21. Five years ago the product of their ages was 28. What is the age of the brother and the sister?

Two bikers A and B start and ride at 75 km/hr and 60 km/hr respectively towards each other. They meet after 20 minutes. How far (in km) were they from each other when they started?

If a certain sum of money become thrice of itself in 5 years 4 months at simple interest, then what will be the yearly rate of interest (in %)?

If  x = a + 1/a, y = a - 1/a, then the value of x4+y4-2x2y2

P and Q can do a project in 6 and 12 days respectively. In how many days can they complete 25% of the project if they work together?