Ans: 28%
The area of the larger circle is 25 π cm 2.
The area of the smallest circle is 9 π cm 2.
The area of the middle circle is 16 π cm 2 .
Therefore the area of the ring is (16 π - 9 π) cm 2 i.e. 7 π
cm 2 .
Therefore the percentage shaded is 28%.