Quantitative Aptitude - Arithmetic Ability Questions

A car travelling at an average speed of 72 km/hr takes 9 minutes to travel a certain distance. By how much should it increase its speed (in km/hr) to travel the same distance in 8 minutes?

Badki can bake 45 cakes in 9 hours, Badki and Chutki together can bake 80 cakes in 10 hours. How many cakes Chutki can bake in 40 hours?

A bookseller bought 500 text books for  20,000. He wanted to sell them at a profit so that he get 50 books free. At what profit percent should he sell them?

A dishonest shopkeeper professes to sell goods at his cost price but uses a false weight of 950 gms, for each kilogram. His gain percentage is

If 1/2 is added to a number and the sum is multipled by 3, the result is 21. Then the number is

The value of sec217°-1tan273°-sin17°sec73°

A bag has Rs12.9 in the form of 1 rupee, 50 paise and 10 paise coins in the ratio of 3:2:3. How many 50 paise coins are there in the bag?