Answer:
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Step-by-step explanation:
So to complete the square in
ax^2+bx+c=d form
make sure a=1
subtract c from both sides
take 1/2 of b and square it
add that to both sides
factor perfect square
1x^2-1x-2=0
a=1
move c to other side
add 2 to oth sides
x^2-1x=2
take 1/2 of b and square it
1/2 of -1=-1/2
squaer it
1/4
add that to both sides
x^2-1x+1/4=2+1/4
factor left side
(x-1/2)=2+1/4
first blank is 1/2
2+1/4=8/4+1/4=9/4
blanks are
1/2 and 9/4
P(defective) = 3/12 = 1/4
P(good) = 1 - 1/4 = 3/4



The probability that at least 2 units are good is given by:
P(2 good) + P(3 good) + P(4 good) = 0.211 + 0.422 + 0.316 = 0.949.