Answer
$\dfrac{24}{49}=48.98 \%$
Work Step by Step
The area is: $ \text{area of second largest circle-area of a second smallest circle}=\pi (5)^2-\pi(1)^2=24 \pi \ cm^2 $
Now, the total area is equal to the area of the largest circle $= \pi (7)^2=49 \pi \ cm^2$
The probability that the dart hits the blue or red region is the ratio of area of the blue and red region to the total area:
P(dart hits either blue or red region)$=\dfrac{ 24\pi}{49 \pi}=\dfrac{24}{49}=48.98 \%$
