Ganesh Wadkar

You can guess the square root with simple logic.

For example

81.   - sq root is 9

361 is sq root of number whose unit = 1 or 9

Square of 20 is 400 .so u can it's square root of either 11 or 19.

If you compare sq of 20 u can easily guess it sq root of 19.

If last digit is 4 then it's square root of either 2 or 8

If last digit is 9 then it's square root of either 7 or 3

If last digit is 6 then it's square root of either 4 or 6

And if it's 5 then 5

given 

h = 15 cm

volume of cone = 1570

to find- radius (r)

formula- 

volume of cone = 

           1570     = 3.14 *  * 15 /3

     1570 *3 =  3.14 * 15 * 

                =   1570 * 3 / 3.14 * 15 

                   =100

taking square roots on both sides , we get 

     r = 10 cm

Diameter of the conical pit = 3.5m 

radius= 1.75m

height=12m

volume of cone= π h /3

                      = 3.14 * 1.75^2 * 12  /3

                      =115.39/3

                      = 38.46

volume of cone = 38.46 m^3

1= 1000 L = 1 kilolitre

hence ,

38.5  = 38.5 kilolitrs

        1.    L^2 = h^2 + r^2              L = slant height   h= height  r= radius

            25^2 = h^2 + 7^2

            h^2 = 625 - 49 = 576

                  after taking square root

h = 24 

volume of cone =                               L^2 = h^2 + r^2

                       = 1/3 * 3.14 *7^2 * 24

                       =3692.64/3

 volume of cone  =1230 cm^3

1L = 1000cm^3

therefore answer is 1.230 L