If $$ \sqrt{0.04×0.4×a} =0.4×0.04×{\sqrt{b}}$$ then the value of $$ {a\over b}$$ is:

A piece of wire when bent to form a circle will have a radius of 84 cm. If the wire is bent to form a square, the length of a side of the square is

Ratio of age of father, mother and son is 9:8:3. Five years hence sum of their age will be 95 years. Find the age of son 5 years ago.

The smallest positive integer when multiplied by 392, the product is a perfect square, is 

If the positions of the digits of a two-digit number are interchanged, the number obtained is smaller than the original number by 27. If the digits of the number are in the ratio of 1 : 2, what is the original number? 

What least value which should be added to 1812 to make it divisible 7,11 and 14? 

The shadow of a tower, when the angle of elevation of the sun is 60° is found to be 15 m shorter than when it is 45°. Then height of the tower is 

If $$ {3x+}{2\over {\sqrt{x}}}=1$$ then $$ {x-{\sqrt{x}}}=?$$