
Andy C. answered 08/15/17
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Math/Physics Tutor
The area of each board is 20(12x +24) = 20*12(x+2) = 240(x+2)
The area of the target in the first board is (6x-3)(2x+4)
Probability = {(6x-3)(2x+4)}/{20(12x+24)}
= {4(x-2)(x+2)/{240(x+2)}
= (x-2)/60
The area of the target in the second board is pi*(6x)*(6x) = pi*(36x^2)
Probability = pi*(36x^2)/ { 240(x+2)}
= 3*pi*x^2/ {20(x+2)}
The area of the target in the third board is 1/2*(3x+6)*(8x) = 1/2*3*8*x(x+2) = 12*x*(x+2)
Probability = 12*x*(x+2)/240(x+2) = x/20