The shadow of a tower standing on a level plane is found to be 30 metre longer when the Sun's altitude changes from 60 ° to 45 °. The height of the tower is 

A number is decreased by 20% to get another number. The number so obtained is increased by 200% to get a third number. The difference of the third number and the original number is what percentage more or less than the difference of second and the third number?

The speed of three cars in the ratio 4 : 5 : 8 . What is the ratio among the time taken by these cars to travel the same distance ? 

The greatest number, which when subtracted from 5834, gives a number exactly divisible by each of 20, 28, 32 and 35, is 

Find out the value of $$ {\sqrt{(121)}} +{\sqrt{(12321)}}+{\sqrt{(1234321)}}$$.

In a certain school, the ratio of boys to girls is 7 : 5. If there are 2400 students in the school, then how many girls are there?

The angle of elevation of the top of a building at a distance of 70 m from its foot on a horizontal plane is found to be 60°. Find the height of the building.

A shopkeeper gives rebate of 20% and 10% successively on print price of a chair. If cost of chair is 2,000, then how much amount will customer pay?