if the radius of a circle is diminished by 10%, then its area is diminished by

[A] 10%

[B] 19%

[C] 20%

[D] 36%

let the radius of circle = r units

area of circle = pie r² .......(i)

it is given that the radius is decreased by 10 percent

therefore radius becomes 9r/10

area of new circle = 81/100 pie r²

area diminished = pie r² - 81/100 pie r² = 19/100 pie r²

percentage of area diminished = (19/100 pie r² ) / (pie r² ) X 100 = 19 percent