If radius of a circle is decreased by 11%, then the total decrease in the area of the circle is given as:

20.79%

Decrement in the radius = 11%

We have a concept ,

If the radius is decreased by x% then the change in its area is given by = x + x - \(\frac{x^2}{100}\)

The total percentage decrease in the area of the circle is = 11 + 11 - \(\frac{11^2}{100}\)

= 22 - 1.21 = 20.79%