Quantitative Aptitude - Arithmetic Ability Questions

In the following question, select the odd word pair from the given alternatives.

If on a Sale there is 40% discount on the marked price of Rs 1000, but the sale is done at Rs 510 only then what additional discount (in %) did the customer get?

If a + b = 9 and a2+ b2= 61, then ab is

A certain sum of money triples itself in 5 years at simple interest. In how many years it will be five times?

How many numbers are there from 2000 to 7000 which are both perfect squares and perfect cubes?

A trader buys 500 kgs of cotton for Rs 9,000. 10% of this cotton is spoiled due to rain. At what rate (Rs/Kg) should he sell the rest to earn 10% profit?

The brother is elder to his sister by 6 years. Seven years ago the product of their ages was 72. What is the age of the brother?

When 0.090909.....is converted into a fraction, then the result is