If 72 men can build a wall of 280 m length in 21 days, how many men could take 18 days to build a similar type of wall of length 100 m? 

There are three containers of equal capacity. The ratio of Sulphuric acid to water in the first container is 3 : 2, that in the second container is 7 : 3 and in the third container it is 11 : 4 . If all the liquids are mixed together, then the ratio of Sulphuric acid to water in the mixture will be: 

A trade buys 800 kgs of tomatoes for Rs 7200.  10% tomatoes are damaged in transportation. At what rate (Rs / kg) should he sell the rest earn 30 % profit? 

If the number 247_679 is completely divisible by 9, then the smallest whole number in the place of the blank digit will be 

Ramesh stands 40 meters away from the foot of a tower, if the angle of elevation of the sun is 60 degrees at that point, what will be the height of the tower?

What is the value of $$ {cosecθ\sqrt{1-cos^2θ}}$$.

Find the value of ∠OBE=?

$$ \sqrt{.081×.484\over0.0064×6.25}=?$$