Question

a circular plot of ground radius 42m is surrounded by a ring of grass plot. Find the width of grass plot,if its area is equal to that of the circular plot

Answer 1

Radius = 42m
area of ground= 2*22/7*42*42
                       = 5544m^2
area of ground = area of grass plot
then,
                          =5544m^2=5544m^2
add the both area for total area of circle
                          = 11088m^2
                11088= 22/7*r^2 
        11088*7/22=r^2
                  3528=r^2
                59.39 = r
radius of total circle - radius of ground
               59.39 - 42 = 17.39
                
width of a grass plot is = 17.39m                                Answer.....