An article was sold for Rs.4000. Had a discount of 10% was being offered, the profit would have been 20%. The cost price of the article was:

A train crosses a platform in 30 seconds travelling with a speed of 60 km / h. If the length of the train be 200 metres, then the length ( in metres ) of the platform is 

The length, width and height of a room are 10 meters, 8 meters and 6 meters respectively. What will be the largest bamboo length that can be kept in this room?

A clock showing the time of 8 o'clock in the morning. How many degrees will the hour needle rotate in the clock by 2 pm?

The ratio of the number of boys and girls in a college is 7 : 8. If the percentage increase in the number of boys and girls be 20% and 10% respectively, what will be the new ratio?

The twice of sum of the ages of a father and his son is 8times the age of the son. If the average age of the father and the son is 28 years, what is father's age? 

When a number is increased by 24, it becomes 115% of itself. What is the number?

If tan α = 2, then the value of   $$ {cosec^2 α - sec^2 α}\over{cosec^2 α + sec^2 α}   $$ is :