Answer: A. 51%
Step-by-step explanation:
Area of circle = [tex]\pi r^2[/tex] , where r = radius of the circle.
In the figure below, we have the complete question.
According to that,
Radius of outer circle = 7ft
Radius of inner circle = 5ft
The probability that the thumbtack will be placed on the inner circle
[tex]=\dfrac{\text{Area of inner circle}}{\text{Area of outer circle}}\\\\=\dfrac{\pi (5)^2}{\pi (7)^2}\\\\=\dfrac{25}{49}[/tex][π is canceled from numerator and denominator
in percent, [tex]\dfrac{25}{49}\times100=51.0204081633\%\approx51\%[/tex]
So, the probability that the thumbtack will be placed on the inner circle = 51%
Hence, the correct option is A. 51%.
